If you want to window shop locally, and/or buy off a shelf, perhaps walk through Microcenter @ 9294 Metcalf Ave. or window shop at:
http://www.microcenter.com/search/se...ortby=pricelow#
and pick the OP store.
Larger selection than Best Buy or others, and usually better pricing.
Leilani's post is nice inexpensive HP machine, note that its a refurb mail order. That said, one of my road warrier machines is an HP Pavilion and its still kicking and screaming after four years of seriously heavy use.
Must have Windows 7 or more recent, and at least 4GB of memory, or whatever Apples current is if you go that route.
If you're going to dispose of the old machine, there's more needed to sanitize the data drives than just deleting. Ask.