What is your budget?
Looks like a good build.
Sli isn't usually recommended. For the p[rice you don't usually get that much of an improvement, and one newer card could outperform the older sli.
PSU is good, but a bit overkill. Nice price for that though.
I would stick with 4gb of ram now. Nothing that the average user uses will take advantage of the 4gb, let alone 8gb.
Not sure about the 45nm quads.
What OS are you going to use? A 32 bit OS will only see 3.5gb of ram max.
It's coming....just you wait.