I would have a look at a Sandybridge upgrade (1155) rather than the 1156 you mentioned. Perhaps a P67 motherboard with a Intel i3 2100 CPU. This would cost around £ 140/150 with plenty over for a decent bit of ram. I am on the iPad at the moment so cannot,very easily price up components for you. But have a look at Scan Computing and Ebuyer,two stores I use regularly, and price up your needs. I'll have a look tomorrow if you want.
Sent from my iPad.