I got a GF 5600 Ultra 256MB card when my GF 4600 Ti 128MB card blew about two years ago iirc. Fortunately, I got it as a quick fix for about $200. I say fortunately because the card is crap... it's not even faster than the 4600 Ti, even with being newer, double the memory and DX 9 combatibility.
Thankfully, I had upgraded that to a GF 5950 Ultra 256MB within a few weeks and relegated that card to auxillary status on my old computer back then.
If you're buying a new card on the cheap, get a Radeon 9800 Pro 256MB; that is still a killer card for the price. If you're willing to spend $250-$300, get a Radeon X800 XL 256MB: the absolute best card in it's price range hands down. $350-$400 gets you a Radeon X850 XTP 256MB card, which I can say is just awesome, having received one free last week... three weeks after upgrading my GF 5950 Ultra to a X800 XL for $250.
