Here are some suggestions:
Size: You will see 12" screens up to 17" screens. Try to get a widescreen, they are nicer usually. If you are planning on carrying a laptop around to school everyday, look at the smaller sizes. You will regret having a 17" 8 pound computer after a couple weeks. the 12" ones are usually around 3-4 pounds and are much more portable.
Processor: this affects speed of your computer. I suggest avoiding Celerons and getting pentiums (Pentium M, Pentium 4, and Intel Centrino are all pretty much synonymous). 1.6 Ghz is a very affordable speed as is 1.8 Ghz. avoid the 2.0+ Ghz unless you have lots of money to spend (you are spending about $200 more to have a computer that only runs 10% faster = not worth it IMO)
RAM: This is the computer's temporary memory. If you have less than 512 Mb, your computer will run pretty slow especially when you have lots of applications open. I suggest 1 Gb (1000 Mb) of RAM, and you will see much faster performance. Note that most places overcharge for RAM. If you want to save some money, buy a computer with less RAM and buy the RAM seperately from another source. (PM me for details) This is especially true if you want lots of RAM, like 2Gb+
Hard Drive: You only really need the 40 Gb drives, but usually it is only like $70 to $100 to bump that up to 80 Gb, so go for that. Again, dont get the 100 Gb unless you have lots of money (costs $100 more than the 80 Gb).
Video: In larger laptops you will see separate video cards, in smaller laptops you will see "integrated" video cards. Seperate ones are better, but unless you are planning on playing video games I would not worry about upgrading anything here. IMO, for school a smaller laptop is better anyway.
Also: Make sure you get the Integrated Mobile (Intel Centrino = integrated mobile, otherwise get it as an option). Extended Warranties are usually unnecessary; 0-2 years is plenty, especially when they charge $200+ for them. SOmetimes you are given a choice of battery. Get the cheaper one (4-cell) and you can save some money here too. the more expensive ones last longer, but you can't recharge them as many times and plus they are twice as heavy . . . so it is not as worth it as they make it sound.
CD-ROM: Dont get teh DVD burner unless you do a lot of video editing or you back up your system often. From your post I assume that you really dont get into that stuff. Usually they add about $50 to $100 to the price of your computer, you probably wont use it that much, but if you have th extra $$ it isnt bad to have on the other hand.
In summary, don't just go out and spend all the money you have on a laptop. I disagree with the previous post that says you should buy the best you can afford. The reason why is that there are some things that you need and some that you do not. And most of the time you are paying way more for a feature that you will not use, or does not overall improve your system that much. Saving money on your computer will not make it go obsolete that much faster. If you follow the above guidelines you should be able to get a good laptop for $1,000 to $1,600 and will be able to do anything that anybody else's computer will be able to do.
