I dunno.
DH and I recently swallowed really hard, and blew out tax return on a new p.c. and new laptop. Both are running 64-bit Vista. I thought I'd freak out with it, but so far, the transition has been pretty painless. I still haven't fully moved over our Visor pda desktop apps from our old p.c. (~8 y.o., and I have no idea where the disc is for it) and so far it's running fine (but I haven't tried sync-ing them yet).
We even had our Linux-nerd (said jokingly and with his full knowledge and appreciation) friend help us network the two together, and while he acknowledges that he STILL hates Windows and anything MS, he had to give them props, as it was relatively painless for him.