Just did a test, C drive with 40Gb of Windows + program installs, a default settings initial full scan on a reasonably good machine.
----------- SCAN SUMMARY -----------
Known viruses: 925205 Engine version: 0.97 Scanned directories: 17693 Scanned files: 99960 Infected files: 0
Data scanned: 15352.83 MB Data read: 15506.05 MB (ratio 0.99:1) Time: 2863.965 sec (47 m 43 s)
http://www.eweek.com/c/a/Security/GMs-OnStar-Ford-Sync-MP3-B...
I tend to run clam-av on file servers and mail gateways for the obvious reasons. I like the software, it works quite well. I'm going to have to look into the mp3 block though, this just seems like a bad idea.
You can set an ignore list (at least in the clamwin gui) by default a lot of data files (images, mp3s, avi etc) are set to ignore since they shouldn't be executed anyway unless your player is buggy
