I had Windows Pro x64 and believe me there was nothing , absolutely nothing 64bit about them. Don't now bout vista but i hear
that the same crap goes on but they have improved on the 64bit part... a bit.
A 64bit OS is noting without 64bit applications to run on it.
I decided to go MAC ( as they say ) 1,5years ago and i have to say, i won't use windows for a long long time, unless i have to.
Did not even bother to install them with Bootcamp or parallels.