Media Center Capabilities

Hey, I was wondering, I have a Windows Media Center PC and I am able to record television programs on to my PC's harddrive(so I am guessing I have some sort of capture card). I have an interest in maybe making some machinima and so I was wondering, if I plugged my 360 into AV (yellow, white and red) jack on the front of the PC tower, would I be able to capture footage on to my PC using Windows Movie Maker's capture feature without having to buy a capture card? Your help is greatly appreciated.