While not entirely RPG-related, it's worth noting that Microsoft has finally released their first Service Pack for Windows Vista. The update includes several performance enhancements, while also adding support for DirectX 10.1 and rolling some of the previously released gaming-specific updates (such as the virtual memory space and multi-GPU fixes) into the package.
To put it simply - if you're running Vista and playing games, you should install SP1. You can grab the 32-bit version here and the 64-bit version here.