You'll be fine. The GTS doesn't take that much power, so couple that with the rest of your system and I doubt you're hitting past 300-350W on load. That leaves you with quite a bit of headroom. Also, PC P&C is one of the best PSU companies, so I'm certain that not only can that PSU handle that load, but it should be able to handle even more than it's rated for while remaining steady.
Thanks! My friend said that he was not sure it could do it because it was not on the 8800 gts SLI certified list. I told him that it should not be a problem, but I just wanted a second opinion. I could not find anything on Google about it, so I figured I could find out here.
Well, Nvidia requires 26 amps on the 12 volt rail for a single 8800 GTS, but it's not fair to say you'll require double that amount... so assuming the GTS is consuming half of that 26 and the PC the other half, you'll need a PSU capable of around 39 amps on the 12 volt rails to power your system and the two 8800 GTS.