Hypothetically, if I do buy this power supply, what would be the best GPU to get as well?
(My gpu is an HD 4200, by the way)
I've been thinking about getting an HD 7850, but people have been saying that the 430w isn't good enough.
I'm aiming to stay in the 7850 range, and I'm also willing to get a nVidia GPU, but I wanna note that the PSU above only has one 6-pin connector.
Your cpu is only a 65 watt model. This helps you get by with a smaller power supply.
On paper alone a 7850 should pose no issues for the power supply(it has 384 watts on its 12 volt rail). It will help if the power supply is bottom mounted in the case because it will see cooler air since it is rated at a lower temperature(I think it was 30c or so).
You should be OK. The HD 7850 is only a 130W card at max (10.8amp @ +12V): http://www.hwcompare.com/12032/radeon-hd-7850/
The processor is 65W (5.4 amps @ +12V) at its max. The 32A +12V rail of the Corsair should be fine with that and any small stuff on the same rail. I ran that card and an Athlon II X 2 220 on a cheap Cooler master 460W PSU on a previous budget build and there were no issues. Your Corsair is a much better PSU.