How can I give one program exclusive access to my hard drive and cpu?

My hard drive light flickers on several times a minute, and I can see in the task manager my cpu is occasionally used even if I'm not doing anything. I want to capture video with windows movie maker through a firewire, but I've realized that the video skips after being captured. The skipping definately happens at capture, because: 1 The original video does not skip when played back onto a TV through DV Camcorder, 2 The captured video is about a minute short for every hour of video, 3 The video skips after being transfered to another pc and even after being burned to dvd with another pc and played in a normal dvd player. (original pc has no dvd burner and second pc has no way to capture video) My research suggests that the problem is occuring because of other programs accessing the HD and CPU during capture, and the video does skip more if I run other apps during capture. I've already emptied my HD of all but Windows XP plus upgrades, and I have removed many optional startup apps using msconfig. Is there a way to turn off all background programs safely, or even better, temporarily reserve HD and CPU access for the one program/task?