A VOB file is a Video Object File & is part of the basic file structure of DVD-Video . It is essentially a MPEG-2 file but it can have more than one audio (or video file) running together within the stream.
It will depend on what NLE (Non Linear Editing) software you have as to whether it will deal with VOB or MPEG files. Because of the temporal compression used in MPEG they are not that easy to edit as you can only effectively cut on certain frames (not all the frames contain full data.)
It is possible to convert your VOB files to AVI files (the preferred format for most NLE) for editing but you may notice a quality hit.
Check out
www.dvdrhelp.com for help on all this.