After doing a bit of searching I have found that this is not that uncommon. How many others out there are not running in agp mode without knowing it??
Turned fastwrite off in BIOS, nil help.
Changed AGP setting from 8X to 4X in BIOS and hey presto everything is as it should be. Although in 4X when the card and MOB are allegedly 8X it seems to be one of those compatability issues!!!! I have read that you wouldn't notice any difference between 4X and 8X!
I have downloaded the SiS AGP drivers, although I haven't installed them yet. As it seems to be working not sure if I want to install them, would it make a difference do you think?