Your processor is a bit under-powered for video editing. It rates a 3,400 on benchmark tests, and in my books I usually recommend a processor that rates at least a 6,500 to 8,000 for basic editing. Although you are editing standard definition video, so you may be able to do some basic work.
First thing I'd do is look at the video and see what it's made of. DV-AVIs were once the workhorse of consumer video -- but not all AVIs are DV-AVIs.
Open one of your AVIs in the free download MediaInfo. In MediaInfo, set View to Text and then copy that text to this forum.
Once we know which codec your AVI is using, etc., we'll better know what's going on.