hehe I was just about to say, make sure you check that the ram will work with the mobo on the manufact's website.
the 7900GT (int my eyes) is great for gaming, its a relativly mid-high end card and since your upgrading from a pretty old computer the card will wow you greatly (unless you've seen the latest technology in action at a friends house or something).
I am sorry tho afl mate, I am not very up to date with amds, I dont know whats good and whats not.
and next year I might have to sign up to your forum and get tips on who to pick in footy tippings
Hope you get your computer and all things go well.