Well, it finally gave me back control, (after an hour) all seems well. (but not sure what went on there!)
My Computer 'properties' is showing 504MB memory not 512 (something to do with 8MB aside for video card maybe?)
Before I attempt to add my 2 x 512MBs back in, should they be installed in a special way.. physically?
What I mean is... which slots of the 2 banks should they be installed in, bearing in mind I have a total of 2x256MB and 2x512MB