Don't get the Vapor-X version unless it's the cheapest model. It does absolutely nothing for you. Instead, grab an HD 5770 (usually around $150-160 CAN).
I would also consider dropping from a 620W PSU to a 550W (or even as low as 400W), as you're only running a single GPU. The 5xxx series cards don't need a lot of power.
Drop the X3 435 and grab a 425 for a little less. It's the same chip, just without a facotry overclock.
After all of that, you might have enough to pick up a Coolermaster Hyper 212 (usually about $30 CAN). This will allow you to overclock the CPU to a very high level (I've heard around 3.6 GHz on three cores) and/or unlock the fourth core. This will maximize the value of the CPU.