So no one replied to help
Anyway I thought I would update to help anyone in the future who has this issue.
All this arose when I changed PC's. I have both still running and wasn't going to swap over totally to the new one until everyting was working. The new one doesn't have a dedicated soundcard but gets sound off the motherboard I guess()?) I hadn't bothered switching my speakers etc over to the new PC but ICC suggested that it was possible that the game wasn't loading as there was no soundcard / speakers.
I really thought that sounded like BS to be honest, but I connected the speakers and....bingo.....the game works in both DX9 and DX10 modes.
As I expected the graphics card seems to struggle a bit though even though it is 512MB - once the action gets involved it isn't very smooth and thats at 800x600.