I have a toshiba satalite (think thats how it is spelled) and never once had a problem with it over last year and half, runs fast and no virus.
Now mac is best way to go due to you can instal windows xp onto it and mac is compatible with it. But if you don't know how to use a mac and are very familar with xp, just buy a toshiba...or ive heard even better those sony vio's (think thats what they are called) My friend owns a sony laptop and says it is awsome.
Also a good site, which my friend buys his computer from http://www.ibuypower.com you can make your own computer basically with the best shit...well mainly the best stuff.
But what ever you buy for a laptop, make sure it has a 1.86 GHz processor, even better if its a duo cause then its really like a 3.6 GHz processor but just split up into 2. And 1 GB of DDR-2 ram is also good with the faster processors.
My laptop cost me $1200 canadian