How can I tag movies for use in iTunes/AppleTV? I'm rolling over my AVI's to MP4 for my new AppleTV. 
Is there a good program out there for tagging the movies with their appropriate details? 

Also, I noticed iTunes will get "Album Artwork" for some movies and not others. 
I don't know if that's related though. 
I am doing this conversion on a Windows 7 box.
You can do that in iTunes, select each file and click Get Info on the context menu. You can even tag several files at once if they share common info, such as the episodes of a series.

Also, you can add covers in the same manner. Just paste from IMDB or (as I do) from the iTunes browser previews