how much do you want to spend ? ...
what you have is pretty much non existant nowdays ..
£37 will get you a gt 620, slight upgrade and a half...
http://www.novatech.co.uk/products/c.../nov-6102.html

£40 will double the cores http://www.novatech.co.uk/products/c...s/nov-620.html

£80 will be like having an upgrade with atttitude lol
http://www.novatech.co.uk/products/c...-md2gd3v2.html

just 3 quick options all depends on where you want to stop ..
can play aything with this
http://www.novatech.co.uk/products/c...680oc-2gd.html

however i expect a new pc might be needed to make the best use of it ...