After more research i found that advent pc only has x1 pci-e slots and not x16 which i NEED!!!
So i found another quad core i5 2400 with 8GB RAM and a 1tb hard drive with 6 2.0 usbs 2 3.0 usbs and at least one pci-e slot, on which is already an nvidea gts450 card all coming to £520.
Then my peripherals etc.... Thanks for the help