I would save for new computer - yours is about 3 years old, and the GPU is about all you could upgrade. A new one will have a much better CPU, use DDR3 RAM, and the motherboard will likely have SATA III, and maybe USB3..
Tyvm guys.....with Guild Wars 2 coming out this year (hopefully) I am definately looking to get ready for that game mainly,and perhaps Tera. I have a few months yet to save up. Unfortunately the specs for Guild Wars 2 arent available afaik
Would anyone be able to suggest a new build on a budget of $500-$1000