Wow that's one heck of a machine you're planning to build.
I'd generally agree with skuzzzzy although mushkin memory is hard to get over here and any RMA would have to involve sending it to the US as
AFAIK mushkin don't have any EU returns office
The stock fans on the h70 are not that bad, esp if correctly setup with PWM (almost any PWM fan correctly setup is very quiet) however the gentle typhoon is probably the best radiator fan you can get due to it's high static pressure.
Corsair HX vs AX, the AX is amazingly good and one of the best PSU's around (also look at the Seasonic X) It's going to come down to overclocking, the HX is still good and very solid in performance with great ripple control the AX just takes it a step further and it is probably overkill.
And if you are looking at adding a 2nd gtx480 then 1000w is the range you're looking at, maybe slightly less.
Might also want to look at
900W Enermax Modu 87+ Gold
1000W NZXT Hale90 Power
If you stick to a single gtx480 then a good 750-850w will be more than enough, although I do have a feeling that a high end 750-850w psu could probably cope with a gtx480 sli system as we do tend to over rate PSU needs.
Hard drives I favour Samsung or Western digital, Seagate just doesn't seem to be as good as they used to be.