It's your decision...but if someone gave me an infected system...first thing I would do is eliminate everything that came on the hard drive, I would destroy any existing partitions and do a fresh, clean install of XP.
Even if I know the types and extent of infections and system compromises such system might contain...I believe in starting with a "known good", as opposed to tryiing to "clean up" a "known not good."Others will have differing opinions.
I'd forget about the .mp3s also. Theoretically, they might be safe..but malware is often not what it seems to be and I would see no point in taking the gamble.
You might look at some of the topics Here.