SpacePhoenix makes some very good points. I just wanted to add that if you are looking to purchase something for business, you should get a PC that is easy and inexpensive to maintain. Some people may need specialized or less popular computers to do specific tasks. For example if you are into graphic arts or similar work, a Mac may be a better buy but if you are doing a lot of general purpose business activities (i.e. emailing, word processing, spread sheets, presentations, internet surfing,etc) then something that has broader appeal and that is compatiable with mainstream business related software (i.e. Microsoft office ) would be a good buy.
I’m partial to the Dell latitudes but that’s just my opinion. Toshiba also makes a good machine.
Also, if you go with windows, get 7 first until they work all the bugs out of 8.
Hope that helps,