I'm not a windows user per se, but you do need to be aware that some music files themselves have viruses imbedded within them. So I'd suggest a very good scan of these is definitely needed with an AV with up to date virus definitions. A starting point: Virus thread: Typical virus spam file sizes - Make a note of them (click on blue link to see)

I do hope others add their suggestions here, since I am predominantly a mac OSX user, so need input from a windows user here.