Microsoft completed testing two hotfixes and has released them for direct download on their website.

It is very important that you apply these two hotfixes on your systems prior to testing. They address a number of stability and performance issues in both DirectX 9 and DirectX 10. Without the hotfixes, you may experience crashing or performance drop offs. Many applications are affected, including BioShock, Company of Heroes, Call of Juarez, Battlefield 2142, Half-Life 2 and others.

The first patch, KB940105, tackles problems caused by graphics cards with large amounts of onboard memory, such as 512MB or more. The second patch, KB936710, is amusingly titled "When a DirectX 10 application runs on a Windows Vista-based computer that has multiple graphics cards, the computer does not use the secondary graphics card." Such a thing might be a problem for a SLI or CrossFire rig, no? The problem only affects DirectX 10 applications, and it's very straightforward: "the operating system does not forward driver-render requests to the secondary GPU." Hence, the second graphics card may be no help whatsoever in DX10.

Obviously, most folks with decent gaming rigs will want to consider installing one or both of these hotfixes. Nvidia put it to us this way: "They address a number of stability and performance issues in both DirectX 9 and DirectX 10. Without the hotfixes, you may experience crashing or performance drop offs. Many applications are affected, including BioShock, Company of Heroes, Call of Juarez, Battlefield 2142, Half-Life 2 and others." Before installing them, you'll probably want to install earlier updates for Windows Vista that address performance and compatibility.