Two PCI cards will not be usable on the A8N32-SLI M/B you'll only have the use of the PCI slot in between the 2 PCI-E slots.
Look at the A8N32-SLI M/B layout the PCI slots next to the PCI-E slots are useless because of the graphics card cooler knocks out the use of PCI # 1 & 3 leaving # 2 useable.
Look at the EPoX EP-9NPA3-SLI M/B layout the first PCI slot gets blocked by the graphics card cooler, leaving PCI 2 & 3 slots useable.
The EPoX EP-9NPA3-SLI is just flat out a better M/B, I previously had an ASUS A8N32-SLI that died on me and besides having only 1 useable PCI slot, the clear CMOS jumper was located at the end of the second PCI-E slot, which aligned it under the 2nd graphics card, a really bad location.
But don't take my word for it look at the M/B layouts, with the ASUS I constantly had sound trouble with my Creative Sound Blaster X-FI soundcard but not the first time with the EpoX M/B.
I'm presently running 2 7800GTXs in SLI mode, which fit nicely over the active chipset cooling fan, which doesn't make hardly any noise at all, so in my opinion ditch the ASUS idea and go with the EpoX.