Not sure about DS3 compatibility, but I have those modules currently in my backup PC. They did DDR-940 with 2.1V going through them, not too bad for low-mid end sticks. An even better choice would be the GSkill with the blue spreaders that grishkafool is running. They're a pretty good price, and work well in an 8GB config, which is a testiment to their quality. You'd be good with either, however the Corsair would limit your FSB to ~450MHz or so.
Looks like a good choice pf parts. Case is nice, and a decent cooler too. HSF is perfect.
Link to the GSkill RAM, it's 1066 too:
Newegg.com - G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory Model F2-8500CL5D-4GBPK - Desktop Memory
Forgot to ask: What PSU will you be using with the build?