I've already looked into Vista Game Explorer (lots of docs on the MSN website).

Most of it should be easy to implement, my only worry is how to handle the "Authenticode Signing" process (mostly because legal stuff drives me crazy). So far I haven't found a clear answer to "Do I need to use Authenticode to use Game Explorer?". I know it is required for a rating, but I hope it isn't needed just to run (it's a added expense and hassle for indie developers).