I installed Windows 7 64-bit on my main machine last night on a blank hard drive and so far I'm very impressed. It's Vista, but with a snazzy new taskbar and noticeably better performance.

Under Vista, when in Dalaran my five shamans would be lucky to get 5fps each. Now, my main gets 25fps and the four clones are all at their 15fps cap. This is very encouraging. I'm just worried that Microsoft will use the months before official release to pack a load of bloat into it and slow it down again.

The latest Vista 64-bit Nvidia drivers work fine. The rest of my hardware was supported by Windows straight off, apart from a couple of "unknown devices".

One small thing to note, if you install Win7 on an unpartitioned disk, it will create a small 200MB partition at the beginning of the disk to conform with the EFI standard (See http://en.wikipedia.org/wiki/EFI_System_Partition). If your disk is already partitioned and formatted before you run the installation you can avoid this happening, although I see no harm in it myself.