Windows 7 Clean W7 64-bit Install & Drivers

Have you tried running the Link Removed should help answer some of your questions.
I assume you've already confirmed that the processor on the computer supports the 64bit version of Windows 7, so your main concern will be, as you seem to already know, is going to be drivers.
I think that you will find that a lot, if not all, the vista 64bit drivers will work on Windows 7, but it might be a good idea to download them in advance and burn them to a CD or DVD just in case. Also you might have better luck if you know the manufacturer of a specific hardware device, checking with the manufacturer's website as you will often find more current drivers available through that resource

Most network drivers will at least work in Windows 7, so you have a good chance. But I have the fortunate situation where mine does not (Z68).

If you do not have an install CD or DVD, doing what Trouble suggests and download ahead of time will save you time.

The Chipset drivers and such are a different matter. I always download them from the website and install, but of course I need the basic drivers for the network.