My first partition runs Vista Home Premium x64 and my second partition runs Win7 x64 RC 7100. I have been using the Win7 partition as my primary os since it was installed and have no regrets as it is extremely stable and more than meets my current needs.
Kept the Vista for the Win7 upgrade (clean) processes and I am moving all related info, docs, software, etc to the Win7 RC partition to hold until the primary partition is rebuilt with Win7. Then Bye-Bye RC partition 2 and hello single partition and system tweaking. It will be nice not to have to keep two partitions up to par but what can you do.
Have been testing Win7 on my DELL Latitude C600 1ghz/512meg ram and it appears to run extreamly well other than AREO which I don't need there anyway. I will restore XP back prior to the Win7 upgrade (Thank god for Windows Home Server and full system restores). Home theater still runs Vista Home Premium and I plan an in-place upgrade just to test without a clean install as it is just an entertainment system which can be rebuilt if necessary but from what I've heard it probably won't be necessary.
The one thing I will say is my Vista partition is ROCK STABLE and doesn't give me any heartburn since SP1 and some tweeking of the system to make it work my way. The system is good enough if Win7 wasn't available but it is and it is what we Vista users were promised a few years ago when Vista rolled out. Long delay and quite a few lie's on M$ part but they did finally get it right. Sad it took so long. Purchased 3 copies of Win7 Home Premium during initial half price sale (Disappointed with M$ over family pack being same price as once again they show their disdain for the loyal customers) and a lack of a Win7 Professional family pack is just plain dumb. I guess they don't think anyone with a home network would want or need things like bit locker, RDP, or XP compatibility because everyone knows that the home users can afford to purchase all new peripherals to go with their new Win7 pc's. or upgrade to Professional to get full use of their Windows Home Server.