If you've got the budget for all that, I'd say that set up is pretty solid. I like your choice of motherboard. 650i is the way to go, 680i's are a joke from what I read in a couple reviews. Performance is marginally if any bit higher in a 680i over a 650i and if you're not running SLI there is
zero performance increase. Looks like you did your homework.
I'd say go for it.
On second thought, if you want to go ahead and get a x64 OS (winxp pro x64, vista x64) get 4GB of RAM. You'll find many new games coming out soon can benefit from it. It's only about $100 more for twice the capacity.