If you are having problems playing Sirius satellite radio online with any operating system, including Vista, you need to download a reliable codec pack like K-Lite Mega Codec Pack. When you install it, if you have any other codecs installed it will ask you to uninstall first, which it will do for you. Then you can just do the default install of K-lite. If it finds any problems in the registry with broken codecs it will ask you if you want to delete them from the registry, click yes!

Here is the link to download the latest version from a reliable site. Trust me, this works. I fixed my friend's laptop with Vista on it this way. Very simple.

http://www.codecguide.com/download_mega.htm

Enjoy your Sirius!