I just found that it's possible (for me at least) to get the / in AC/DC to stick. This is how I did it.
I'm running XP pro SP2, using MP3 Tag Tools v1.2 found here (free):
http://massid3lib.sourceforge.net/
It seems like XP is confused when both ID3v1.1 and ID3v2.x tags are used.
Artist "AC/DC" must be in the ID3v1.1 tag and cleared from the v2.x tag!! You can use just the 1.1-tag but then you loose lyrics and picture if you have them. The rest of the info works ok from the v2.x tag. You can have both, as long as they do not use the /.
If you later on write id3-tag-info from iTunes (and others?) this wil mess up your Artist info again in Windows XP Explorer. Guess iTunes copies the artist into the v2.x-tag.
Seems like the / in the v2.x-tag upsets Explorer. Other mp3-programs may be perfectly able to read this correct info, though.
/ 
