What card should I get?

Hi everybody I have been in a conundrum for awhile and I thought id take it to the experts.

I just recently upgraded my system to a Q6600 (a little late but the only quad that would work on my crappy unoverclocked intel board with 1066fsb). I also got a new PSU with that "GameXStream OCZ700GXSSLI 700W." I here are my current specs.

Intel DG965WH
4GB DDR2-800
PNY 8800GT 512MB
INTEL Q6600
OCZ700GXSSLI
OS's: Vista Ultimate 64bit on first HDD and Mac OSX 10.5.6 (hackintosh) on second.

I know that all of these I mention arnt going to work in mac, but apparently they will in VESA mode until snow leopard so Im not to worried.

Heres What Ive Narrowed it Down To

4850x2 2gb
GTX 280
GTX 285
Possibly a GTX 295 or 4870x2 but not really.

What i'm trying to say is should I upgrade now or wait? Also if I shall upgrade which card has the best value?

Or should I wait awhile and make this a spare PC for the home and build an i7 when I get the money. I really dont want to spead alot. I just can't decide.

Thanks so much!