How good a graphics card can i get?

Which is thermaltake brand and model ?

Im not quite sure it comes standerd with some of the cases (mine is the v4 black addition)

DC OUTPUT +3.3V +5V1 +12V1 +12V2 -12V +5VSB
Max Output Current 25A 28A 14A 15A 0.3A 2.0A
Min Output Current 0.5A 0.3A 1.0A 1.0A 0A 0A

It's a terrible psu, it has a dual rail +12V with 14A and 15A, i recommend getting a new psu with the card if possible depending on your budget.

Ouch, those are some 'old skool' specs, gives you a MAX of 348W on the 12v rails - note that that is max (they can say that if it mantains power for 1/10 of a second at that draw - seriously). You will want to replace that PSU or look at a GPU that does not need additional power to it, a GT640 or something.
I personally would not plug that into an expensive graphics card

thank you, I recently upgraded to the 640, so are you saying that I cant go any higher than the 640??

I wouldn't recommend it until the PSU is replaced with one of newer design and higher quality. This link is excellent (IMO) for finding PSU reviews (and generally learning what makes a 'good' PSU) http://www.realhardtechx.com/index_archivos/Page541.htm
As an FYI here, 99% of the time we will not recommend getting a PSU/Case combo. What usually happens is the older designed (seems to be the case here) and or cheaper built models get put in those cases - there are rare exceptions and they're gems when found. But that is very rare and exceptional
Because your PSU's design is old we're pushing for replacement with a quality PSU and is why the PSU review link is included

So what would happen if I did upgrade graphics card it said its a 500 WATT psu, i dont understand about the amps and why they matter please explain  

Because it's on the +12v rail that it will feed the cpu and gpu, the two most important things, if a psu only has 14A, it means it can only deliver 168W for those, meaning a cpu within 70W and a 140W gpu will be above the minimum required, it's a better factor then just to look for the fake total wattage in some cheap psus.

So your saying that it can only deliver a certain amount to certain parts, also how hard is it to get a new PSU and install it? Thanks

It's easy, the new psu will have all the connectors necessary for your system, in fact a quality one will have even more sata connectors and two pcie connectors.

Wow ok then, thanks for your help

Best answer selected by Quadacon.