you need a new graphic card. its really bad quality.
It may not be bad quality (the quality
may in fact be stellar), but extremely low-performance.
Your e8400 should have some life left in it.
What you get should depend on your budget and your PSU. If this is a name-brand prebuilt like Dell or HP, with a typically weak (but not junk) PSU, then get a HD7750 if it is at least 250W. If it is only around 200W, then you'll be limited to a HD6570. If it's an off-brand PC (e.g. an eBay special), then the PSU will be of uncertain quality, so do not trust it for any more than half of what's on the label, and even that may not be clean (e.g. Logisys, Diablotek, Apevia).
If your budget allows, you can get a 450W Antec VP-450 for around $39. Unlike most PSUs that lack active PFC (and have a little voltage switch), the VP-450 is actually an efficient, modern design. That PSU will run a much heftier graphics card; basically anything with a single PCIe power connector (and a few with two, like the HD7870).
If your budget is not much over $150, I'd get the VP-450 and a HD7770. If it is closer to $200, the VP-450 and a GTX650Ti would be a good, balanced choice for your CPU.
Even if you were to "go overboard" on a nice 650W Seasonic PSU and a HD7970 or GTX670, those items won't represent money wasted because you can use them in your next build; either of those cards will be bottlenecked by your CPU though.
Edit: I'm assuming your PC is built in a standard mid tower case, with a standard ATX PSU. If it is a slim case, your choices will be limited. There are quality 350W PSUs available in the smaller SFX and TFX form factors, but the most powerful low profile card that is readily available I believe is the HD7750. Even so, it will offer a day vs. night difference over the GT610.