Recommend a Card Nvidia/ATI

I'm looking to build a computer for scratch. I'm allocating $250 max
for a new video card. Right now, I'm looking at buying a Chaintech
GeForce 5600 Ultra. From everything I've read, it seems like ATI puts
out a better mid-range graphics card. However, I'm more apt to trust
Nvidia for compatibility purposes. If anyone has any experience with
any of these cards, I'd love to hear your opinions.

I've got both a gf4 ti4400 ( bit older I know) and a 9700pro. Both are
excellent cards, though the ati one is the better card of course. I have had
no problems with drivers and games with it.

The gf4 still performs _sweet_ in games on my 2nd game PC (1333 t-bird)