Want to "upgrade" from 32-bit to 64-bit, h/w question

Hi,

I know I'm sort of late to the party, but I'm trying to "upgrade" my Win 7 Ultimate 32-bit to 64-bit. I have:

ASUS P5K-E mobo
Intel (R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz
8.00 GB RAM (of which, of course, only 3.25 GB is usable with my current setup)

When I built the computer, lo, these 4 years ago, the newegg rep told me that the hardware I bought was 64-bit "ready." IS IT? (Just because I built it doesn't mean I'm not "a better idiot"--I totally lucked out by following the "this is your mouse" grade instructions.)

Can I just load up my Win 7 backup that's been languishing on this flash drive and upgrade?
Or would a clean install be better?
Will it install at all?

I've backed up my docs and settings and stuff, and I hope it will restore from a 32-bit to a 64-bit, or what was the point of backing it up?

Thank you in advance for your help,

Luminosity :confused: