I'm a former IT worker with a degree in Comp Sci/Electrical Engineering and experience with several laptops, so take my advice--STAY AWAY FROM DELL and BUY A THINKPAD or APPLE.
Dells suck. I bought two, recommended several to friends and almost all of them had major hardware failures within 2-3 years. Either the Hard Drive crashed, PCMCIA and Ethernet ports went out of service, there was always something going wrong. And when it does, you will be on the phone with someone in New Delhi telling you to take apart every damn piece of hardware and reinstall it in case 'the connections are loose.'
Its just a very poorly built product, hence the cheap price.
IBM, however, is known to build a quality product and after two years with my thinkpad which is light, has never crashed and has the best keyboard made on laptops--this is important if you plan to type anything but short emails. I'm so used to the wonderful tactile feel of the keys that I find it uneasy to type on regular keyboards now.
If you can migrate from the Windows platform, I'd recommend an Apple, which is truly the easiest to use, will never crash with the new UNIX based Tiger OS. The best partof Apple is that it has true plug-and-play capability--connect all kinds of peripherals with no drivers or I/O errors like you have with Windows.