Right now, you can order a retail 8500 for $150, or a retail GF4 Ti4400 for $235 at the Gateway store, after $50 coupon and with free shipping. You'll always find a better deal if you wait, particularly if you're willing to wait two months for a 4200 to appear, but $235 for a 4400 now (or, within a week or two, anyway) is a great deal. Or you could get a Visiontek GF3 Ti200 for $100 after a $50 MIR, also using the $50 Gateway coupon. It's your choice.
But if you don't have a decent (>1GHz + DDR) PC, you won't see much improvement from the top-of-the-line cards--you're probably better off upgrading your CPU than buying a GF4 Ti.