You'll need a modem if you want to be able to connect to the Internet from your computer. The final thing to look for is software. If you're buying a PC, make sure you get Microsoft Office 97, specifically you'll want Word and Excel, you may also want PowerPoint. Word is the standard word processor on campus and Excel is the standard spreadsheet software. Most computers come with a version of Office 97, but if they don't, you can buy an educational copy at the bookstore for a reduced rate.
Most software is sold at a reduced educational rate for students and teachers.