Motherboard memory = DDR2 667
PCI Express revision 1.0 and it does support SLI. It is incorrect to assume any video card will work, some of the latest models only support the newer style UEFI BIOS.
That said a GT710 is a slightly older Kepler GPU, so it should be okay.
The memory on the GPU having a 64bit bus and being DDR3 or GDDR5 will not matter.
The computer would be compatible with 64bit OS as well.