The Internet is your direct line to the outside world--so it goes without saying your Internet connection better be speedy. Average Internet users will find a 56K modem works just fine. If you need to upgrade, a variety of v.90 modems, typically for under $75, are available from 3Com (http://www.3com.com), Diamond Multimedia (http://www.diamondmm.com) and Practical Peripherals (http://www.practical.com).
If Internet usage is extremely critical, consider the latest ISDN, cable or xDSL services, depending on availability. At a minimum, these solutions will double your access speeds compared to a 56K modem. Call your local phone and cable companies about availability, pricing and the need for additional lines and equipment.
Bredin also recommends seriously considering a domain name for your business, so your e-mail address isn't with some generic ISP. An e-mail identity with your company name, like Steve@XYZcompany.com, lends an extra level of credibility. You can get one from Network Solutions (http://www.networksolutions.com).