Using Windows Live MM with Win 7

And, yes- I made a 'complex' project. (13 mins long) I have it all on one timeline, but of course, learned that I should've made it into smaller ones. (& that I'm probably gonna have to convert All audio to .wma format?) Got the "missing files/ remove unusable objects" error message when I tried saving. I converted all the video clips to .wmv, though all the audio was mp3. (I had no trouble with mp3s before)

My question is- is there a way for me to take what I have on my timeline, copy half of it & save *that*? (& then do the same for part 2?) Or do I have to do this clip-by-clip??

Should I just get the older MM or what?