I would say, look towards a gtx 750 ti. Because the 650 ti requires a PCI power source.
Look at this one, it'll perform better
http://www.newegg.com/Product/Product.aspx?Item=N82E16814487024
Or this one, it's a non SC edition
http://www.newegg.com/Product/Product.aspx?Item=N82E16814487025
They're about the same price. But here's the problem I have. That 450 watt PSU, like I asked, is it a computer from someone who built it? (Like HP, dell, or a 3rd party builder) so the power supply worries me. Because most of the time, they cheap out on it. Why I recommended the 750 ti, because
1. it uses less power
2. It doesn't need the PCI e cable to get its power
3. It will beat the 650 ti, good thing is that it comes with 2gb of memory, and comes in the same size. Don't get those dual fan cards, but then you'll need more power for it.
I would say, also get a better quality PSU, from Corsair. But I would like to know if it's a computer from Dell or something.