This week I conclude my three-part series of articles offering tips for buying a laptop.

The series began with a comparison of reader survey results from PC World and Consumer Reports (subscription required). The results showed that Lenovo and Apple deliver the most reliable products and the best service and support. The next article offered a look at top laptops from Lenovo, Apple, and Acer (which also did fairly well in PC World reader surveys), and gave advice on best times to buy a new laptop.

This week I'll cover the best places to buy a new laptop; how much to pay for it; and how to finance it.

The Best Places to Buy
In late 2007, PC World and Consumer Reports both published reader surveys rating the best places to buy computers, both online and in brick-and-mortar establishments. Here's the consensus:

Online. Above-average ratings in both surveys went to Newegg.com and Amazon.com. In the PC World survey, both earned better-than-average ratings in the categories of Best Prices, Product Selection, Shopping Cart Experience, Site Design, and General Satisfaction. Also scoring well in both surveys were Apple.com, Buy.com, and Costco.com.

I've bought computers or accessories from Newegg.com, Amazon.com, Apple.com, Buy.com, Dell.com, HP.com, and a few others. I don't have a definitive favorite. However, I highly recommend Dell's Outlet for those looking to buy a refurbished laptop. Buy.com and Amazon.com often have compelling prices. And Costco is known for its generous return policy--you have up to 90 days to return a computer.

Brick-and-Mortar. Apple stores earned the most better-than-average scores among PC World readers and were the favorite retail stores among Consumer Reports readers. The free in-store workshops and Genius Bars (offering free in-store tech support by appointment) are two reasons why I love Apple stores. Costco earned top marks among PC World readers for Best Prices, Return Experience, and General Satisfaction and did well in the Consumer Reports survey, too. PC World readers rated OfficeMax better-than-average in two categories: Return Experience and Store Design, though Consumer Reports readers were less enthusiastic.

How Much to Pay?
Prices on new laptops can vary wildly, from $255 for an Eee PC to $5084 for a Dell XPS M1730.

To determine the laptop that fits your budget and needs, ask yourself a few questions:

Are your computing needs fairly mainstream? If you aren't looking for extreme power or ultra portability, an under-$1000 laptop will most likely meet your needs.

Is portability important to you? If so, keep in mind that thin laptops sometimes come with a heavy price. Expect to pay $1500 to $3000 or more for a full-featured, Windows- or Mac OS-based ultraportable.

Are you looking for a powerful desktop replacement? Here, too, you'll pay more than you would for an all-purpose, mainstream laptop. The majority of computers on our Top 10 Power Laptops chart are priced over $2000.

How to Pay?
There are lots of ways you can pay for your new laptop. Take a few minutes to consider your goals before buying.

Are you trying to earn mileage points? Spending $1000 on a laptop could earn you 1000 frequent-flyer miles, depending upon your credit card. You may earn even more miles by purchasing through an airline frequent flyer membership program's shopping portal. In my experience, though, you won't find the best bargains this way.

Are you looking for the most warranty for your money? Many credit card companies automatically double a manufacturer's warranty, so keep this in mind when considering an extended warranty from the computer manufacturer or retail store. Note, however, that the computer maker or retail store's extended warranty/service plan usually includes tech support, which you won't get from the credit card warranty.

Do you want to avoid paying interest? Some retailers let you charge big purchases without interest, as long as the balance is paid in full within a particular time frame. Example: The Amazon.com store card lets you make minimal monthly payments without interest, as long as your balance is paid up within two years. Alternatively, upon checkout you may be able to use Bill Me Later, a service that lets you avoid using credit cards and make no payments for 90 days.

Do you want to lease or buy? Leasing a computer may offer some advantages over buying. For example, depending upon terms, a lease could make it easier to dispose of your laptop later. Though my article "Lease or Buy?" is nearly four years old, the pros and cons outlined are still relevant.

Adding It All Up
If you closely followed this series of articles, you might buy a MacBook Pro from the Apple store right after new MacBook Pros were announced, then pay for it with a credit card that earns you mileage points.

That's just one strategy you might decide upon. Whatever you do, I recommend taking time to consider the six criteria outlined in this series:

Who are the manufacturers with the most reliable products and the best service?
Which laptop models consistently get the best reviews?
When is the best time to buy a laptop?
Where should you buy it?
How much should you pay?
How will you pay for it?
There are other factors to consider, too:

How will you use the laptop? Will you take it on the road, say, 90 percent of the time? If so, consider an ultraportable. Will it primarily sit on your desk? Then you're a candidate for a powerful desktop replacement model. Is your answer somewhere in between? Then you probably need an all-purpose laptop.

Do you really need a Windows laptop? Given how unpopular Vista is, and how elegant and inventive the Mac OS is, I recommend at least considering Apple's laptops before you buy. That's particularly true if you aren't beholden to a corporate IT department and you don't use a lot of Windows-only software every day. (Yes, you can run Windows applications on any current Mac. But if you need support, to whom will you turn? I have no personal experience in this, but I've heard that neither Apple nor Microsoft is inclined to bail you out of Windows-related issues on Mac hardware.)

Do you really need a brand-new laptop? You can save hundreds by buying refurbished computers. In my experience, Dell's Outlet is unsurpassed in its refurbished purchase options. Read more about Dell's Outlet in "Finding Deals on Portable Technology."

If you've got tips or suggestions for other readers about how to buy a laptop, please send them to me.

Lenovo's Flashy Ultraportable: Lenovo has jumped into the stylin' laptop market with the IdeaPad U110. The ultraportable comes in fire-engine red , with a laser-etched lid and rugged rubbery base coating. The computer weighs 2.9 pounds and comes with a 120GB hard drive (at a slow 4200 RPM). It delivered decent battery life in our tests: 4 hours, 38 minutes on one charge. But the glossy screen can be difficult to view in some lighting conditions, and the laptop is not inexpensive (our test unit was $1900). PCW Rating: 76 (good).

HTC's Touch Dual: The latest version of this Windows Mobile phone features a slide-out keypad and other promised improvements. But the keypad can be difficult to type on; ditto the on-screen virtual keys, which are bunched together. And the phone's screen is a bit smaller than the original Touch, to make room for the keypad. HTC moved the MicroSD slot to a more convenient location, however. This GSM phone comes unlocked, but at $550, it's expensive.

Backup Strategies: Worried about losing all your Microsoft Outlook e-mail and other data, should your Outlook database become corrupted? One solution: Set up a Gmail account and sync your Outlook messages to your Gmail account using Gmail's IMAP option. You can learn more about this tip (which I've tried and recommend) and other backup strategies with Rick Broida's "How to Prevent a Data Disaster."

Contributing Editor James A. Martin offers tools, tips, and product recommendations to help you make the most of computing on the go. Martin is also author of the Traveler 2.0 blog. Sign up to have the Mobile Computing Newsletter e-mailed to you each week.

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