You can step up if you buy a eVGA 6600gt, you then have the option of sending your 6600gt back when you want to upgrade to a eVGA 6800gt. You just pay the diffrence between the 6600GT and The 6800GT.I'm pretty sure thats how it works...Nubius did it a while back,ask him.
mathfreq- it seems you can't go wrong with Ledtech, eVGA, or chaintech. I own a XFX 6600gt and absolutely LOVE IT!!! The thing O.C's great and i've never had any trouble with it....BUT it seems everyone craps all over it in these fourms when anyone asks. Don't believe the HYPE!!! The best thing to do is to take the recommendations you have been given and then do some research on the internet (google it) and check out some other computer fourms and see what they have to say. Good time on buying the 6600gt's because prices have dropped the past little while.
INTEL PENTIUM 4 3.0 GHz
512kb L2 Cache S478/ Zalman 7000B-AlCu cooler
Antec Solution Series 3700AMB Case 350W
XFX GEFORCE 6800GS VF700-AlCu VGA cooler
1 GIG CORSAIR/1 GIG GEIL DDR400 PC3200
Benq Lightscribe 16x DVD ReWriter
SAMSUNG 1.44MB FLOPPY DRIVE
WESTERN DIGITAL 80GB 7200RPM 8MB CACHE HARD DRIVE
Philips 17\" MONITOR
LG 52X24X52 CD-RW
Logitech MX518 Optical Mouse
MICROSOFT WINDOWS XP HOME