Joining MPG clips into one file/title

I'm looking for a good piece of software that will join my clips into one MPG. I've tried a few and wasn't really happy with the results. I've just downloaded about 6 more to try out but I was wondering if any of you had opinions on this subject.

I have two needs. One: To join DVD compliant clips (made by DVD Shrink) into a single title. I've found that making a DVD with a great many different titles is problematic. My player doesn't like to play the DVD correctly... It is difficult to navigate... If I were to merge the many clips into a few titles I would be able to add chapter points and navigation would be much better.
Two: Merging short clips from various sources into one file.

Thank you
Brian