The phrase "you can't polish a turd" springs to mind, but if you're really set on shortening it's life then
http://www.overclock.co.uk/customer/...=16752&cat=413
will cool the GPU, but the memory will probably also need cooling if you're going to overclock it
http://www.overclock.co.uk/customer/...=17622&cat=413
Hardly worth it, you may as well put the money towards eventually buying a decent video card.