Well yesterday the graphics properties weren't offering 1080p and I scanned for hardware changes, but still it wasn't available. I guess following a reboot it's now there and I've set to 1080p. Maybe your suggestion was enough to make it perform properly.
I may still be interested in the graphics card root though as it's quite a nice screen connected via VGA, so any advice on potential cards would be gratefully receive.
Thanks for your help.