Eee PC 1000HA with Windows XP -- $325
Acer Aspire with Windows Vista Home Basic -- $250 (open box)
Same model, new -- $290
Lenovo G530 with Windows Vista Home Premium -- $370 (open box)
Unless you plan on gaming, all of these should be sufficient for schoolwork. If you plan on gaming, get a desktop; it's cheaper to get a cheap laptop and a gaming desktop than a gaming laptop. Note that the Eee PC lacks an optical disc drive.
Dell is horrible. Don't get a Dell. Just because you've heard of the brand name or haven't tried anything else doesn't mean it's a good brand. They're the single worst brand I have ever had to deal with. Their computers regularly overheat, their hardware fails early at best, the computers come pre-loaded with the most bloatware I've ever seen, and their technical support is staffed by monkeys with books.
Netbooks are a very good option for both the budgetwise and the fashion-chic as they are "in" at the moment (expensive ones are also available).
Oh also, twocows, please dont call it the "single worst brand" as you havent tried enough of their products, unless you own a computer store or you have a very good money flow to buy most of their releases.
Dell has always been very good in quality and customer service, but ever since the incident with leaking batteries in Latitude 110L, D530 and Inspiron 1100, 1150, 5100, 5150, and 5160; people have been making bs about Dell, and this has just become a bandwagon for ignorant people to jump on.
Hardware is top quality with Dell, and so is their software, but all that software does clog up your system, so you use brains and only install drivers, and only install compulsory software such as Biometric Devices.
Oh yeah, that reminds me; get a netbook from a supplier and it may also give you Windows 7 for free when its released as an offer (it will tell you so in the information somewhere)
I would advise you not to buy a notebook / netbook from ebay unless its sealed by manufactor as they may be second-hand, or have a defect (hey the world's not black and white)