I'd reccoment DDR2-6400 (800MHz) RAM as its better suited to the E6600.
Go for a Tuniq Tower 120 cooler, its quiet and will let you overclock the E6600 to at least 3.6GHz.
As far as a PSU is concerned go for something name brand and >500W. If you are looking for quiet, Seasonic make quiet PSUs.
Case - I've no idea since I'd use a decent size case, its the quiet factor that does it for me. Antec P180 is quiet, and cool. But its big....