On August 7, Microsoft released two fix packages for Windows Vista. The Vista performance fix pack, KB 938979, (both 32- and 64-bit versions) is downloadable here. http://support.microsoft.com/?kbid=938979
The reliability fix pack, KB 938194, (32- and 64-bit flavors), can be downloaded here. http://support.microsoft.com/?kbid=938194
These updates resolve some of the performance, compatibility and reliability issues discovered to date. The updates should be available on Windows Update sometime next week, however they are available now at the download center.