Personally, I've found almost Nothing that I've needed or wanted that won't run on Vista 64bit. Also, almost All major hardware makers now have 64bit drivers for things as it's now been awhile since 64bit started to become more mainstream and they've caught up. In the beginning there were a few h'ware makers still in Beta with drivers, and some not even at that level yet, but those days are almost gone now.
One thing I WILL strongly suggest tho, is the
Vista Codec Pack by Shark007 and make sure you get the 64bit pack, and the Tool package is also very handy. It's a compilation of all available working CODECS in one lightweight package and takes care of the Biggest Vista headache...CODECS.
Also, like Roy asks...which scanner do you have? My scanner's maker didn't release any Vista drivers so I was out of luck until I found
Vuescan, which makes my scanner even more functional now than it EVER was with the original driver/program on XP.
It now supports over 750 flatbed scanner models and it's not free but WOW..is it a Lifesaver for folks like me with a 5 year old scanner that's no longer supported.
You'll like 64bit, even tho you can't really find anything that's fully optimized for 64bit yet, but that's not far off either.
Good Luck!