If your going to buy a new card, and money is not an object, I would get the RADEON 9700 PRO, or wait for the GF FX. Otherwise, go with a GF4 Ti 4200 - 4600 or RADEON 8500 - 9700. You can look up specs for both here:
http://www6.tomshardware.com/graphic/20 ... index.html
Good prices here:
http://www.pricewatch.com
http://www.newegg.com
Just read the card info. Try not to buy a LE RADEON card or a MX GF card. Also, try to avoid OEM.