If you'll look around on this forum you'll see that this comes up pretty regularly and there are a couple of issues you'll need to deal with.

The first issue is whether or not the DVD is copy-protected, as most commercial DVDs are. If that's the case, you're going to get gibberish.

The second issue is how to get the file into your computer for editing. If you have an analogue-to-digital converter or you can use your digital camcorder as a pass-through, you can sometimes bring in the video as sort of a faux-AVI, in which case you may be able to cheat around the MPEG issue.

But the third issue is that DVDs use MPEGs (or VOBs, which are essentially MPEGs) and MPEGs are a delivery format, not an editing format. See, MPEGs don't hold separate information for every frame but rather have a key frame followed by several frames that base their information on that key. This results in very high compression (which is why MPEGs are so much smaller than DV-AVIs). Unfortunately, it means that, if you try to edit it, you can sometimes run into problems, like strange flickering.

Does that answer question?