I've never been able to play .VOB files using Windows Media player - it tries, but puts up a lot of speckling on the screen - not really worth watching.

But, in answer to my own query, for anyone who is interested - I have found that Gom Player (www.gomplayer.com) will play almost every type of video file, including .VOB files.
Unfortunately, there is no editing capability with Gom Player.
Tony