Aces can be run at decent frames for around 500-600 at the cheapest I'd imagine.
In the US pretty much so. I recommend looking for information on this forum (Hardware and Software) from the last half a year. There's even a new thread about the subject going on, but lots of good information has been given in the previous ones.
Outbreak has a point too in Frankensteining your old rig. If it was built for gaming, the case at least should work, as well as the optical drive. They aren't worth much, but a saved $70 is money after all. Some other components could be usable, too. Send specs, we'll tell.