You'll be making a mistake by buying any FX card right now, IMO, but I suppose a great price could compensate for their slow DX9 performance. But a 5900XT for $190 is a mistake when you can buy a 9800P for the same price, a card which will be faster overall, particularly in newer, DX9 games.
The 6800 is a pretty good buy, too. If you don't want or need Far Cry, consider the MSI 6800. It has a decent bundle, too, and it has a custom cooler that's quieter than the stock nVidia one. GamePC.com has a review of the MSI.