I'll agree with Jeba. VirtualDub, as a video capturing tool, leads the pack. It's quite flexible when it comes to handling capture cards or TV tuners. If you want to go truly psycho geek, then try DScaler as it has the most elaborate configuration options and supports almost any TV card out there.
However, in you case you just want to 'cut' (and not actually capture) video from a big movie file. If it's MPEG, DAT, etc you can alsy use MyFlix as it will directly cut and save the video. VirtualDub is better suited to handling AVI files. No comments on VOB since I don't have a DVD drive.