we used to buy dells at my previous employer - what is great is that you can congire it exactly as you want. only had one problem, which was some bad memory. they talked me through it on the phone rather than sending someone out - so i ended up doing all the work.
one thing i like about dell, as opposed to compaq etc., was that nothing was proprietary - i am not sure if compac and ibm etc. have changed. laptops might be a different matter.
i have a dell at home - it is fine. a friend who is a real techie, and used to build and sell computers, sneers at the mention of dell - like anything, the parts are not the best, but you are getting what you pay for. my concern would be some of the local/no-name comptuers advertised in the paper or sold through future shop etc.
one thing with dell - keep a close eye on the ads - sometimes they advertise no shipping costs, and thats the best deal!