It's a good idea to have a bitratecalculator for Xvid etc. included, so that it's easy to create a full fitted CD-R or DVD-R, DVD-R DL etc.
It's always a guess how big a complete recoded movie is getting, including sound and subtitles etc. It's very annoying after a long time encoding, that the total file is only just 20Kbyte to big to fit right on a 700Mbyte CD-R (even with overburning).....
I like a bitratecalculator like for instance AUTOGordianKnot used to have.