When I try to install my new video card I just get a blank screen - Do I need to remove traces of the old system first ?? -
Or should the new one just plug in ??-

You probably need to disable the onboard video in the BIOS at bootup. Depending on the motherboard manufacturer, the key you must press at startup is different. Sometimes it's Delete, sometimes it's Esc, sometimes it's F2 or it could be something else. Once there you'll have to find the setting for something like Onboard Devices or similar and disable the onboard video chip.

Thanks - Mine is Dele - I will restart and retry -

Ok . Once you change the setting, be sure to then disconnect the monitor from the integrated graphics port and connect it to the one on your new video card.

The onboard only seems to have 3 settings in BIOS - PCI ~ AGP ~ Onboard AGP - - Set to AGP ??
ASUS mother board - P5S800-VM

Yes, AGP would be correct .

Thank you exile360 - We have triumphed again - I actually missed this post and just assumed that was what you would say -
I will now go and look for the latest drivers etc. (And play for a while) -

Excellent !

Have fun playing . You can also now uninstall the drivers for your integrated video card if you'd like, as they're nothing more than a waste of space now. Just use Add/Remove Programs and uninstall the SiS drivers you installed previously.