With I tunes you can edit the tag on a single file or multiple files at once.  Just select, right click and get info.
 
 You can also put the album art in your self if Itunes 7 can't get it automatically for you.  Just find the album art online (200x200 - 300X300 is best) and just copy and paste it into the artwork field in the proper space in the "get info" area.  to add artwork for a whole album, select all the songs, do the get info routine, and just past the art work into the proper field.
 
 I don't really see the value in that other program.