I was thinking that yesterday. The computer is 3 1/2 years old, I've replaced the hard drive, the mother board and the modem, so it's not outside the realm of possibility.
Why not buy a killer card, pop it in, and see how it goes?
You will then have it for when your new machine is assembled.
It's like a high-speed connection, once you've had it, nothing else will do.
bbl