For regular businesses the $300+ E-Machines, HPs, Compaqs and Gateways are cheaper by far to buy with Vista and replace with XP if you need to.
It’s cheap now.
Dual core processors, 2 gig of ram, 400gig HDs, burning everything with monitors for well under $400 for desktops.
May laptops sell for $450 or less.
Enjoy the ECS etc motherboards you get in those pre-builts.
If your time is worth anything you'll lose the savings in lost time.