You want to spend less than £60?
First of all make sure your PSU (Power supply) is able to handle the new graphics card. Really you need a PSU of more than 400-500w.
You can get some bargains on Ebay if you look around for a graphics card. I bought a Nvidia Geforce 8800GTS 640mb for £60 back in October on Ebay and while it isn't the best card around and it's around 2-3 years old now it is still a good card that can handle 3D well. Much better than my old Nvidia 7050 onboard chip did. I can play GP4 maxed out with no lag at all.