I have a 6600 GT and was looking to upgrade to one of these choices.
7900 GT lowest power consumption, least expensive ($260-$300)
7900 GTX ($450-$500)
X1900 XT high power consumption, loud, ($350-$400)
I mostly play BFME2 and other RTS games but also a little HL2, Far Cry, and GRAW...