Windows ME can't write to CDs so you must have used a package like Nero's INCD or Roxio's DirectCD. If you install the same name package on XP that CD should become readable.
If you don't have that, ISOBUSTER (see google.com) is an alternative.
I had an old computer using Windows Mellennium and I saved files to CDs. My Service Pack 2 Xp will not allow me to read the Me files. Anyone have a fix for this? I need to get important files from this CD? Appreciate your help.