Im already using a laptop with wireless keyboard and mouse, linked to a remote monitor anyway. So I think the Desktop is my best option, more bang for the the buck, plus as already mentioned if the graphics card is poor it can be upgraded. The Advent is about my price limit unfortunately, as the £3k system looks amazing, but doubt I would get away with spending that.
Thanks for the advice, off to PC World in the morning to get the desktop, so should have it running by the PM, will let you know how it copes.