Coolmax PSU's are not the best, but overclocking your CPU will not add more than about 25 watts to the power consumed by your system.
One of my systems has an OC'd Q9550, 4 GB RAM, a GTX260 - a card with similar power requirements to yours, a Gigabyte EP45-UD3P motherboard, 3 hard drives and an optical, and a Soundblaster card all powered by a Corsair 750TX.
Running 3 instances of Prime95 to load the CPU and 3DMark06 to load the GPU, it pulls 375 watts from the wall as measured by my Kill-a-Watt meter. Figuring 80% PSU efficiency, the system pulls 300 watts from the PSU.
I estimate that your system will consume 325 - 350 watts at full load (slightly greater than mine because of 16 GB of RAM).
deadjon,
We posted nearly simultaneously. The problem with Coolmax PSU's is that they are overrated. For all practical purposes, Bnic has a 500 watt PSU.
I have a couple of Coolmax PSU's running low-spec systems here in Saudi Arabia. Not bad PSU's provided you derate them 20%.