It seems like just yesterday I upgraded to Vista x64. It was a pain in the rear, display drivers did not work, things were a little difficult to get intalled (sharepoint development environment). Some of the main software I used did not work, like screen (screen capture app), pdfprinter, and even simple things like Cisco VPN. It took some time but the x64 vista was worth it. I had a machine with 6 gigs of ram and I could use it. I was not hampered with using XP and limited to 3.something for RAM.
Today I was reading a quick link on twitter regarding x64 and the steam network. It seems that for windows users x64 has taken over 32bit. Here is a link to their hardware survey that shows 40% of windows users being x64
That is pretty good. Since Windows 7 has only been out for a short time. My feeling is that most new computers are now coming with Win 7 x64. In fact, I have not seen an add that did have 32bit any more. Why would you, it limits the RAM usage to 3 gigs.
64 bit has gone a long way since I first switched. I now use 8 gigs of ram and many virtual machines… I would never want to switch back.