Early performance tests of the latest build of Windows 7 have shown it's significantly faster than Vista and XP (and still outperforms both with 1 GB of RAM):
No, its a beta with a designed "time out" period. If you want Vista without the visual glam, look for a torrent of Windows Small Business Server 2008 (its Vista based) and google for "Windows 2008 Workstation Tweak" -- its a program that'll knock off most of the server components and free up like 1.5GBs of HD space.
It should leave you with a thin, responsive, vista-based OS that looks a lot like Win XP/2K with some Vista influence.
http://blogs.zdnet.com/hardware/?p=3236&page=2