Use a i-link or firewire cable (IEEE1394, if you know the standards). Two names for one single cable. Both your camcorder and your computer should have a ilink/firewire connector on it.
If you computer does not, spend around $10 on a firewire card for your computer. You won't regret it.
http://www.newegg.com/Product/Product.asp?Item=N82E16815106002USB isn't really good for this. I used to have the problems your describing with USB. I think its dropping frames, in which case there are some options that you can use to correct this. Unfortuately, I have never used movie maker and am not sure if it even has these options.