I cant really comment on the motherboard since im not too familiar with AMD products. The RAM looks good, but the PSU - ive not seen many people on TOMs go for the GS range. Usually people tend to go with TX or HX - check out some reviews for the GS range or wait for a few more replies here. JonnyGuru is a great site which reviews PSUs.
To use SLI you have to have the same cards. So you cant have a GTX 560 and GTX 570 they both need to be either 560's OR 570's.
You could get a single GTX 570 now, or even a single GTX 580 which will allow for great future expansion if you decide to SLI either of those in 6months-a year down the line, and they will both play all current games maxed out with at least 30 fps on a single card.