I downloaded and installed Windows 7 64-bit beta and I must say I am impressed. It's rock stable (not a single crash in over 2 weeks) and the performance is great.
However, one annoying bug
1. Screensaver won't come on - turns out that if the gadgets are enabled, the screensaver won't come on and the monitor won't turn off! I solved this by typing UAC at the start prompt and brought up user access control and I turned it off. By turning off UAC you automatically disable gadgets (that's a wierd pairing as well). Anyway, now the screensaver turns on. Hopefully MS will fix this soon!
2. Media center Windows 7 - Works great but I couldn't get it to play back the old style DVR-MS files without crashing. Turns out there is an update from MS that must be installed. Here is the link:
3. Playing the new media center's wtv files is also a pain on your older vista machines! The solution was to download "Media Center TV-pack" - you can search for it on the internet. I upgraded my existing vista sp1 machine with the TV-pack and the 2 additional updates and the PC Player runtime (if you search you'll find all this bundled together for easy download). Now the WTV files play on the older vista 32 bit machine. I didn't do a clean vista sp1 install before installing TV-pack and it seemed to still work ok