its a dimension e521 with a radeon x1300 in the pci express port, I would rather get a card I can just plug in without getting a new power supply
£150 to £200 to spend
ATI Sapphire cards anygood?
What is the rating of your AMD processor? And what are the specs of your PSU?
Generally speaking, cards is your price range are rather high end, so you need a rather fast CPU and and a good power supply.
If you don't have at least a Athlon X2 6400+, I would not bother to look for cards in that price range, cheaper ones will be more than enough.