My impression is that laptops are required by schools that don't have enought computer lab space to go around. There are pretty much two types to consider when you're looking. The "desktop replacement" is typically very fast and powerful but also large and heavy. This would be like the Dell Insprion 5100 or 5150 series. They're both great and use the intel pentium 4 processor but they are not considered ultra portable.
The 300m and 600m are very portable and have great battery life, but they are a little less powerful and much more expensive. They use the intel pentium M processor. The speed ratings are not really comparable between an M processor and a P4 processor because of different architecture, so don't think that a 1.6 GHz Pentium M processor sucks... it doesn't.
Keep in mind that some schools also expect that you have MS Word and MS powerpoint installed. I tried to get away with Wordperfect because it was so cheap, but I had forms to fill out in Word format or email attachments that had to be in Word format. You can buy Microsoft Office 2003 Student Edition for 99 bucks at most places, so DON'T pay $250+ to get in pre-installed on a new machine. Office includes Excel, Word, Outlook, and Powerpoint. I've heard that IBM has some great laptops, but I don't have any experience with them. Try for 512MB RAM so that you won't have to upgrade for a while. 30 gig HD is fine for most things. Wireless can either be integrated or on a PCMCIA card. Either one is usually less than 60 bucks.
have fun shopping
