I've been running Windows 7 Ultimate x86 on my laptop for a month now and it's so damn sexy. I had trouble activating it, but it was soon resolved. The system is very responsive and PS Lightroom does much better job now. RA2/YR run without any problems, the same is valid for TW/KW and RA3. Haven tried TS and TD, but they should be working with the thipx32.dll fix for XP.
When I get back home for the Holidays I'll surely upgrade my home PC to Windows 7 Ultimate x64 and my laptop too, but for now I'm sticking with the 32-bit version.