I am no expert, but:
Will you be using it as a Media rig or just a daily computer? Either way, I would say that the 650 is plenty of power. All my hardware combined don't come close to maxing out the 750 I bought. I haven't had any problems with it, but it's still young. However, iirc Antec cut it's teeth on PSUs, so they seem to be reliable. Therefore I agree with the guys above me about the TP.
The 2600k @ 4.4GHz
Intel Core i7 2600K @ 4.4GHz5W idle
That leaves a boat load of power for what ever. Heck, a GTX580 draws ~280 Watts, that still leaves 250w for RAM and Drives!
From a review I found:
It is always a nice surprise when you find out the a device work better than you had expected it to. We knew that Antec had been making big steps in getting their power supplies to be better regulated and with it generate a much needed fan base. With a price tag of a little more than $100.00 this is the perfect power supply for someone that needs a bit more power to run either dual video cards or a larger processor and large amounts of memory. Whether it be a replacement or a new power supply same yourself some change and go for one of these you won't regret it.
I just used the extreme power supply calculator
for a firstname.lastname@example.orgGHz with a GTX560Ti and 4 sticks of RAM and came out with 392w at 100% load. I then added 2 HDDs, a TV Tuner card, and an optical drive and got 456w. Not sure how accurate it is though.