16.6Amps on a 450W psu is ABYSMAL!
At this time of year, there are lots of sales on quality psu's.
I suggest you get a start on next year's build and buy a quality psu now.
A 550w psu will let you run most high end graphics cards, up to a 7950 or GTX670.
You will need something like that to run metro and other games at high settings.
This Antec 620W unit is $50 after rebate:http://www.newegg.com/Product/Product.aspx?Item=N82E16817371059
If you want to upgrade now, I would not try any graphics card tha needs a 6 pin power lead, even if you have one on your psu.
If you push a cheap psu too hard, and it fails, it can damage anything it is connected to.
About the strongest card that would be safe would be a 7750.
Much better than your GT610, but hardly a strong card.
If you want more now, plan on a psu upgrade too.