I have my eyes on some of this but I think that price is steep for 2133.
Should trust in another brand like Mushkin for RAM? They have some lower prices for the same speed and I think the timings are even lower stock too!
The Corsair is more expensive because of the included fan. Phenom X4 CPUs won't run RAM at 2000 Mhz. but many X6 CPUs will. Bulldozer has a default 1866 Mhz. RAM speed. In reality OC'ing RAM produces very small gains today due to the high frequency and bandwidth of DDR3 RAM. There is almost zero performance difference between DDR3 RAM of the same speed because one cycle time is less and less in real time as the frequency increases. Thus a CAS 7 and CAS 9 DIMM will have almost identical *system* performance even though the CAS 7 will look great in synthetic benchmarks.
It's OK to upgrade your RAM and add more if you are using Win 7 or an O/S that supports more than 4 GB. All I was trying to point out is there isn't any point in spending money for faster RAM than you can use. 2133 Mhz. should be fine even for Bulldozer. With your X4 965 you should be able to OC it to 1600 Mhz. as long as you buy RAM specifically matched, tested and approved for the AMD Phenom II X4/X6 CPUs.