Could it be likely that it's not the graphics card and it's your PC? What is you motherboard and your PSU? Your PSU might not be able to handle it and then the graphics card starts becoming unstable. Maplin are a very good reputable company you know.
A good PCI graphics card is this click here or this click here but I wouldn't suggest spending more than £40-50 for a PCI graphics card. If you really want to play games and stuff, upgrade your motherboard and get a AGP graphics card. PCI cards ain't worth it anymore and in a few month's time, you will be looking to buy another graphics card.