I am using free and powerful MusicBrainz Picard program to clean-up my entire MP3 files collection.
Aside of actual job (pooling MusicBrainz database and fixing, sorting, correcting and cleaning-up tags in your music files), it can also rename actual files on your disk in the same time.
The thing is that it uses a very complex filename pattern by default, while I am using something as simple as:
%artist% - %title% $num(%tracknumber%,2). %title%
First for standard files and second for parts of albums. Thus, I have written them down here to keep in mind.