Hate to say it, bit I am really impressed!! Did an install of the 32-bit RC on an "older" P4 with 768K of memory, fully expecting Windows to either refuse to install or break down in the process -- and it worked! Had to manually install the 8-year-old network card drivers (originally Windows 98, then upgraded to XP), but after that, Windows Update found the other drivers and I was good to go!
And now that it's installed, it's every bit as responsive as XP, maybe even faster.
Only complaint is that it doesn't have Aero, but that can be easily remedied with WindowBlinds.
You'd never know that this came from the same folks who wrote Vista.