Didn't the google toolbar have a folding@home option at one time? I seem to recall that it did, but I don't know if you had to download a special version to get the f@h stuff included or not, and I'm not sure if it still exists or not.

http://en.wikipedia.org/wiki/Google_Toolbar

According to the wikipedia article, Google Compute (the f@h tie-in) ended in 2005.

-David