Welcome to the forums, newcomer!
That PSU will definitely need a replacement, something reliably built and has at least 550W of power for the entire build. You can also look into a dual channel DDR3-1600MHz ram kit to replace the rams you currently have. As for the processor and GPU, yeah they should be good upgrades from what you currently have though an i7-4770(non-k) would seal the build for a little while.
You will also want to invest in an ssd for that platform to breath some life into it overall. FYI, if you don't replace the PSU after the upgrades, you're going to loose the entire system due to power surge or a PSU blowing up or worse, a fire!