I'm getting ready to buy a new digital camera (probably Canon SD500) and one thing I will use it for it short video clips. I'm just wondering though - is there any major diffference between MPEG 4 and AVI (which the Canon produes) clips? Could I use both in an iMovie if I wanted to? Is there any reason that one or the other is better with a Mac? I realize the camera is not a video camera but I'd like take advantage of the capability to the extent that I can. Thanks! PS if anyone has commetns on the SD 500 in general I'd love to hear them!