Easy CD 5 will not work with XP without a patch, which is free, but doesn't always work. I doubt very much if there is a free upgrade, or patch from version 4, due to its age. Looks like you are going to have to buy the latest version(7) I'm afraid.
Also verions of Easy CD prior to v6 can play havoc with XP. I would get rid of it quickly if I were you.