Question : Problem: Power supply needed for dual 8800 GT's

I am currently about to receive a single EVGA nVidia 8800GT KO video card, and would like to run two of these cards in SLI mode when needed sometime in the future.  A single card requires a minimum of 22 amps on the 12 volt rail, and 24 amps on the 12 volt rail for 2 cards in SLI mode.  I have purchased an OCZ Game X Stream 700w PSU which states has a max current of 18 amps on each of the 4 separate 12 volt rails. The PCI-e rail no. 1 states a max overcurrent limit of 20.5 amps, and the PCI-e rail no. 2 states a max overcurrent limit of 48 amps.

Since most power supplies I've looked at print that they have only 18 amps on 2, 3, or 4 separate 12v rails, I'm confused about why the amp requirements for this graphics card is so high.  I read that you can roughly estimate the amps on a PSU's 12 volt rail by adding all the separate rails together.  Is this true? Does my PSU have enough juice to power two of these cards?

PSU shown here: http://www.newegg.com/product/product.asp?item=N82E16817341002

Answer : Problem: Power supply needed for dual 8800 GT's

A good place to start would be to calculate your 12v needs because there are more components that are going to need some of that power as well. The more components you can identify and put into the calculator, the better.
http://web.aanet.com.au/SnooP/psucalc.php