Socket 2011 is a waste of money. You gain almost nothing over 1155. Right now Intel is refreshing their Sandy Bridge series and releasing as Ivy Bridge which should be a bit faster so I would wait for that.
I highly recommend an ASUS Sabertooth motherboard for socket 1155 and an Ivy Bridge processor (when it comes out) to go with it Rather put more money into the SSD. About SSD's:
Pros:
-super fast
-no noise
-less chance of breaking (no mechanical parts)
Cons:
-price for the size (smaller sizes compared to HDD,but faster)
-must never be fully filled
-defragmenting is a must every week or two
Buy a 256gig SSD and a 2tb HDD to go with it as a storage unit,you only keep the system and important apps on the SSD for faster loading etc.
For the multi GPU config, your PSU will probably barely handle a 2xGTX560, so you just buy a Geforce GTX580 and when it's not fast enough,buy another one and replace PSU.