Yup I hear ya, WMP 10 is great for the kids, they can burn their own discs and synchronise media for their mp3 players with a minimum of fuss, so its a blessing to me. I havent had any copyright issues (yet) and if I do I'll certainly look at reverting to wmp9. In the meantime using a 3rd party tag editor is easy, you dont even have to change anything, just clicking on the suspect file and choosing to 'save tag' fixes the issue.
If you want a fix for the tag misread issue in wnp 9 its here. Might save you having to edit the tags.

http://support.microsoft.com/kb/814129/en-us