Good tag editing utility that can handle XP Media Center dvr files?

Can anybody recommend a good tag editing utility (preferably freeware) that can handle Media Center’s DVR files (I think the extension is .dvr-ms)?

I’ve got a hell of a lot of stuff* on my Media Center PC, and I try to keep up with it, but to date the only way I’ve found to edit the tags (mainly I edit the episode title tag to include the episode number) is to open the file in Media Player, go to the Library tab and edit it there, if it lets me, which for some reason it often does not on the first try. Sometimes not even on the third.

  • I have over 100 GB of Good Eats alone, and Robot Chicken and Foster’s Home for Imaginary Friends just started new seasons.