Look for something called Speed Step, that is another name it goes by.
The ram market has been shaken up because a lot of ram that has been recommended for a long time have gone out of favor. Crucial ballistics used to be the best stuff, but they got cheap and they are no longer recommended.
I use OCZ gold's and OCZ platinum's in my rig, they seem to work pretty well. I don't know how much support I can get for those brands, but that is what works for me. The golden heat sinks are nice too.
That's a wise move with the xigmatek. HSFs are getting to be huge. Nehalem boards will have a bracket already, but for the time being anything bigger than the stock hsf should get one.