Intel 975X ATX Mthbrd
2GB Corsair
2x seagate 250gb harddrives
snd blaster sound card (forgot which one)

Is it worth the extra $400 to crossfire my HD2900 XT if i only have an Intel Core 2Duo E6700 2.66ghz processor?
Will I be able to last a long time w/ such a setup? Or would it be a better investment to replace my processor?