This might sound cheap-o, but I'd go open box ...
nowdays you don't need the best/most expensive PC to have alot of power ...
I just got an open box HP desktop for $549 (512MB RAM, 2.06 GHz AMD, DVD, CD-R, some cool video card that I really don't need).
Laptops are naturally a bit more expensive, but the moral is that you can usually buy what you need waaaaaaaaaaay cheaper than what you can afford.
In fact, a super-techie friend of mine buys refurbished laptops with broken monitors and sets them up as switches .. lol - they're power efficient, relaible & < $200