AVI cropping assistance?

I have all the (current) Merlin episodes in .avi format but they’re marginally too big for a DVD (just a few Kb) which I can combat by removing a) the “the adventure continues…” preview of the next episode and b) the closing credits

I don’t like to have to do this, but this way I can get each series onto 1 DVD alone

can anyone recommend easy, free software to crop the file from around 44:00 to 42:00 per episode and tell me which codec and compressions I will need to use in order to make the output file smaller than the starting file? 
I don’t want to be losing a lot of quality on the files, as the woman I am making the DVD for has a large TV set and the files are already at rip-quality…