Windows vs. Mac. This is a matter of preference. I use both regularly, and I'm not going to argue that one is inherently better than the other. Do make sure, however, that your school is prepared to support your choice. Linux is a viable choice on campuses, but if you are sophisticated enough to set up and run a Linux box, you don't need my advice.
Laptop vs. Desktop. Each has advantages and drawbacks. Laptops take up less space in cramped dorm rooms and, of course, they are portable. They also tempt thieves, who are distressingly common in dorms. So if you do go with a laptop, get a Kensington lock -- and use it. Desktops offer much more performance for the buck, bigger hard drives, and larger displays. If you are into arcade-style games, laptops can't hold a candle to the video performance of a good desktop.
Specifications. Unless you have some particularly intense need, any processor being sold today will be more than adequate. Don't spend a lot of money for processing power you don't need. The easiest and cheapest way to increase performance is by adding memory: 128 MB is the minimum, especially if you are planning to run Windows 2000. Get the biggest hard drive you can, especially if you are planning to download or rip a lot of music. A CD writer is a good choice; if you can get it, one of the new combo CD-RW/DVD-ROMs is even better (DVD writers won't be generally available until some time next year.)
Tiny little laptops are cute, but that small display will get old fast. Try to get one with at least a 13.1-inch display or plan on using an external monitor.
You'll want at least a 17-in. display with a desktop, 19-in. if you have room for it. Flat-panel display prices have crashed in recent months, and they make good space-saving alternatives -- though still more expensive than CRTs. Fifteen-inch flat-panels run about $500, 17-in. units around $1,000. Because of a difference in how they are measured, a 15-in. flat-panel has nearly the same viewable area as a 17-in. CRT.
Nearly all campuses offer wired Ethernet ports in dorm rooms, in labs, and often, in classrooms. Your life will be easier if you get your computer with Ethernet built in. A built-in modem is actually less important: With Ethernet, you'll find that you'll rarely use the modem. Fortunately, most computers come with both.
Wireless. The wireless standard known as 802.11b or Wi-Fi is the hot new thing on campuses, with service available in dorms, classrooms, labs, sometimes even outdoors. If you go for a notebook, try to get one that has wireless built-in or, at the least, wireless-ready with a built-in antenna. (All Apple models, desktop and laptop, are wireless-ready, awaiting only the installation of a $100 AirPort card.)
No choice here. All new Macs are now shipping with both OS 9.1 and the new OS X installed. Since there is currently very little OS X software available, you'll probably want to use 9.1 for the time being, but you can easily switch at any time.
Windows. If at all possible, get a machine with Windows 2000 installed. The only real downside is that most arcade-style games won't run. But you'll have an easy upgrade to Windows XP, which will run games, when it ships in October (most machines sold this summer will have a coupon for an upgrade.) If you can't live without the games, try for a machine running Windows 98 Second Edition -- though they are very hard to find. If you can, avoid Windows Me, which doesn't get along very well with enterprise-class networks of the sort you will find on campuses. The best thing I can say about Me is that it's a fairly easy upgrade to XP.
Software. It's simple: Don't buy any that you don't absolutely need right now. The publishers of big and expensive software packages (Microsoft, Adobe, Wolfram Research, Waterloo Maple, Macromedia) offer "academic editions" of their software at a fraction of the retail price. These are generally identical to the retail packages, but are only available at campus bookstores to students with school ID. By Steve Wildstrom