Hey there, im using 64bit windows at the moment, and ive had no problems with drivers, it was only last november i had to be very careful becuase there was a large lack in drivers for my printer.
64bit drivers are very common now for internal hardware components, however peripherals is what lacks at the moment, probably becuase they are considered a luxury? I dunno.
A friend just bought a logitech webcam from somewhere and there are no webcam drivers AT ALL for logitech ones, however creative have a comprehensive list.
Logitech do, however have drivers available for My mouse and keyboard, and surprisingly enough, these were all out of the box.
Another thing that i have had to do, is if i was interested in a hardware component, i would have to email the manufacturers in some situations to get information (eg. Imon Remotes).
There are some really good forums and sites dedicated to 64bit windows which i have got a lot of help from in the past about driver issues, have a google.
The only games that i have not been able to get working so far is Homeworld 2 and RA2. Everything else works perfectly.