You might as well get a new system entirely, because you'd have to upgrade
things like the PSU, as it's only 330W. I'm sure a 650 would work, but it could end up
being at reduced speeds, seeing as the PCIe slot it has to fit into, is probably PCIe 2.0
PCIe 2.0 being slower than 3.0 might slow such a card down, by not giving it enough bandwidth.
Depending on where you are and if it's hot and such, it might get too warm in the case too.
If you've got a budget, I can suggest a new computer for you. You also have to take into account
bottlenecking. So for instance if you got one of the newest GPUs and could fit it in your case etc. etc.
that GPU would be bottlenecked by your other hardware, such as your processor. So if you can afford it,
I'd recommend just upgrading. You can make a comfortable upgrade you can expand upon as you go, for
just 350$. That PC also seems to be running DDR2 RAM and we're at DDR3 currently. If you really insist though,
maybe you should check out the GT 545. Not a super card by any means at all though.