Snake Doctor

I'm having a helluva hard time chopping up some clips.

I have a 250K wmv8 file that is pretty damn good quality.
I trim a 10 second spot out of it, click file-->render as, and then save it as a 250K wmv8 file and its choppy as hell.
I tried saving it as a 512K file and the picture was clearer but still choppy as hell.
Do I need more frames per second or less or what do I need to do to have it come out the same quality as the original?

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