Windows vista is a piece of shit, the demands it places on hardware is excessive and for what... I am yet to be informed of some new capability that Vista has that is not available in Windows.
The biggest improvement over XP is that it looks prettier, many of the so called features that are allready available in Linux and MacOSX had to be dropped from Vista to make the shipping date.
The system is still built on the shakey foundations of NTFS and as such will suffer from the same issues as previous versions of Windows with regards to performance degragation as the NTFS filesystem with its data fragmentation issues and no information about the data stored in the files was used one again as the much hyped WinFS filesystem was dropped.
The system is slow and bloated.. when compared to OSX and Linux and the features are way behind also