There are up some major updates for Windows Vista that have just been published to the web and are available for download.
The Vista performance fix pack, KB 938979 (32 bit & 64 bit versions).
The reliability fix pack, KB 938194 (32 bit & 64 bit versions).
Each of these fixes will be released via Windows Update soon.
The fixes that these KB Articles address will be included in the upcoming release of Vista SP1.