Hi guys. Thanks for all the replies. Much appreciated!
Whether I upgrade this system more comprehensively will depend if I can find a full-time job within the next couple of months. (Just about to graduate from university. Bad timing eh..) My motherboard limits what I can upgrade my cpu to, and I really don't want to spend the cash to upgrade both my cpu and motherboard right now, so I guess I'm stuck with the e6600/AB9 combo.
Pufu's testing results are somewhat worrying, though. If that is true, I would get no improvement whatsoever from upgrading my videocard? That sounds... incredible. I wonder if this would be due to cpu-bottlenecking, or something in the coding that would be eventually fixed.