Is 500w enough?

How many amps does it have on the 12V rails?

I would get a name brand power supply. No name power supply's (assuming it came in a case free) are normal of poor quality. I think with that power supply your really gonna be pushing it I have a similar system with a Thermaltake 500watt power supply and I am pushing it With name brand. I would recommend buying a decent power supply 500watts are greater ( gotta remember if the power supply goes it can take the entire system with it).

Your PSU if fine.

Though if you want to spend $70 for one:
http://www.newegg.com/Product/Prod [...] 6817139004

Or here's a quality cheapy ($10 rebate and 20% promo code = $38 free ship)
http://www.newegg.com/Product/Prod [...] 6817139008

Thx for the info

For the 12 volt load:
The Zalman 9700 implies that you are going to be OC'ing - figure 10 amps for the CPU.
Figure 7 - 8 amps for the graphics card.
Figure 3 amps total for the HD and DVD drive and a couple of amps for the fans.

That's very, very close to the maximum power rating of the 12 volt output.

Since it is a no-name PSU, the maximum outputs are undoubtedly rated at 25 C. (basically little more than room temperature). Under load, Under load PSU internal temp will increase, reducing the the power output.

Try it and see. The first sign that you may need a better PSU will be that the PC will run fine with regular 2D graphics programs, but will do "random" resets and reboots while gaming.