FYI, and I haven't seen this mentioned elsewhere, if you're converting something that isn't a 4:3 aspect ratio, replace "scale=240:180" with "scale=240:-2" and mencoder will automagically calculate the correct height (retaining aspect ratio for square pixels).
This will end up letterboxing your movie when you play back, but for widescreen stuff, this can be better than the alternative. I'm running w/ vbitrate=320, and it looks puuurty.
