Sound: Integrated sound, which comes in two major flavors, will meet the needs of all but the most selective users and audio enthusiasts. AC97 is an older audio standard that has been superseded by HD Audio (or "Azalia"). You really have no reason to settle for the older standard, although the newer tech might carry a modest premium. For the dedicated enthusiasts who would benefit from a discrete sound card, an extra PCI-E slot is easy enough to find.
Storage: Like memory, basic storage tends to be relatively straightforward, but it gets tricky with some of the various options and platform transitions. In the past few years, storage experienced a transition from Parallel ATA to Serial ATA (SATA) and then to 3-gbps SATA. 1.5-gbps versus 3-gbps SATA can make a bit of a difference in performance, but typically only in video editing and other media-heavy workloads.
Most hard drives use SATA, while some older DVD+/-RW drives use Parallel ATA. Most motherboards support four or more SATA ports (even as many as ten), which is sufficient for most users.
eSATA is a relatively new standard for connecting external drives via SATA instead of FireWire or USB. eSATA offers higher performance than the other two, and also supports reliability and manageability features such as SMART (Self Monitoring And Reporting Technology). eSATA is not nearly as common as USB 2.0, but going forward it is likely to be more widely adopted, and it is certainly a better interface.
The other real storage issue concerns RAID, which is standard with many modern motherboards. You can use RAID 0 or 1 with two hard drives; the former increases read and write performance, while the latter increases reliability and read performance. RAID 5 requires at least three drives, and RAID 6 (which is really for businesses only) needs at least four; both are oriented around increased reliability and read performance, with acceptable write performance and less overhead than RAID 1. Most systems simply don't need that many drives, so in many ways 6 is a nice option but hardly a requirement. For video editing and other multimedia-rich tasks, basic RAID 0, 1, or 5 will do the trick and should be a requirement.
Networking: Wired networking is dead simple, as any worthwhile chip set will have at least one integrated gigabit ethernet port. For the most part, Wi-Fi is not necessary for desktops, and most motherboards tend to avoid it simply to cut down costs; it's an optional feature.
Assorted peripherals: On a motherboard, the peripherals can include USB 2.0, FireWire, PS/2, serial and parallel ports, and a floppy drive. Of those options, USB 2.0 is an absolute necessity and FireWire can be nice, but the rest are pretty much obsolete unless you need a a specific peripheral device.
Form factor: The last aspect of the motherboard to consider is the form factor. This is ultimately an aesthetic choice that the chassis for the system determines. Most motherboards use the ATX form factor, with the microATX design meeting the needs of space-conscious users. Quite a few other variants (which are beyond the scope of this article) are available for users with particular requirements, however.
The Specs Explained
In the end, the key to building the right system is to understand how you will use your PC. As we mentioned before, the needs of an office worker are totally different than those of a video editing wizard or a gaming fanatic.
Important consideration: Processor. When it comes to performance, the sweet spot for most users is Intel's dual-core CPUs, as there aren't yet enough advanced applications to make a quad-core a must-have. We recommend a 3-GHz Intel Core 2 Duo, specifically the E8400, unless you use applications (video editing, for example) that are better suited to a quad-core processor.
Somewhat important: Chip set. The best companion for the Intel E8400 is a motherboard based on the P35 chip set. You should choose the specific motherboard according to your desired storage, audio, and memory options.
Important consideration: Memory. A modern desktop PC should have at least 2GB of memory, possibly 4GB for more demanding applications (not to mention Windows Vista).
Important consideration: Graphics. Even if games aren't a consideration, you might want to spend a little ($100) on a midrange GPU such as the ATI Radeon HD 3650, which offers a nice variety of video-output options. For gaming, a more powerful graphics card, such as something from nVidia's 8800 GT family, would be appropriate.
Somewhat important: Storage. Building a nice system but running out of storage space is frustrating. Given the way hard-drive pricing works, using a 500GB hard drive makes sense. Larger models cost much more, and smaller models won't save you enough money. Make sure your DVD drive employs SATA so that you will be able to use it in the future.
Motherboard Shopping Tips
Ready to buy a motherboard? Here are our recommendations.
Pick the chip set first, then the motherboard: The difference between chip sets can be significant, but two motherboards with the same chip set will be nearly identical in performance. First figure out which chip sets will work for your system, and then compare the different motherboards with that chip set.
Understand what kind of system you are building: Are you going for an affordable media PC, an office machine, or a gaming monster? These usage models all suggest different things about the features you'll need. Focus only on the features that are important to you.
Avoid SLI/CrossFire unless you absolutely need it: Enthusiasts always pay an arm and a leg for their hardware, and SLI and CrossFire technologies are for enthusiasts only. Simply buying a new video card instead of going from one card to multi-GPU is much more sensible.
Stay with DDR2 memory unless you need the extra bandwidth and performance: DDR2 is vastly cheaper than DDR3. Unless you are planning to upgrade and reuse the memory in the near future, you should buy DDR2 now and wait for DDR3 prices to drop for a future system.
Unless you really know what you are doing, avoid overclocking features: Quite a few motherboard vendors try to differentiate their products by having them support faster-than-specified memory or other exotic features. Remember, though, that such boards are targeted at enthusiasts and are priced accordingly.
Make sure you have at least one high-performance PCI Express slot: Even if all you want right now is integrated graphics, buying a board with an extra x16 PCI-E slot costs very little, and could save you $100 down the road.