Neowin has posted links to the yet to be released KB articles 938979 and 938194 that improve hardware and software Performance, Reliability and Compatibility in Windows Vista 32-bit and 64-bit. These Hotfixes were released to Beta testers at Microsoft Connect and would officially be available next Tuesday through Windows Update services.

KB938979: Vista Performance and Reliability Pack
Installing this update will improve the performance and responsiveness for some scenarios and improves reliability of Windows Vista in a variety of scenarios. Highlights:

-Improves the performance in calculating the ‘estimated time remaining’ when copying/moving large files.
-Improves the performance when copying or moving entire directories containing large amounts of data or files.
-Improves the performance of Vista’s Memory Manager in specific customer scenarios and prevents some issues which may lead to memory corruption.

KB938194: Vista Compatibility and Reliability Pack
-Installing this update will improve the reliability and hardware compatibility of Windows Vista in a variety of scenarios.
-Increased compatibility with many video drivers.
-Improved visual appearance of games with high intensity graphics.
-Improved Vista reliability in networking configuration scenarios.
-Improved reliability of systems that were upgraded from XP to Vista.
-Increased compatibility with many printer drivers.

Download the above mentioned Hotfixes for Windows Vista 32-bit here and for 64-bit here

Update: KB938194 is now officially available to public.