Temps in my passively cooled system er pretty good, watertemps: 23c max no matter what, 32c cpu idle with 1.85 vcore (2364mhz barton) all DIY. Radiator is a small livingroom radiator - 4L of water all in all. My girlfriend's older brother bought that Reserator cuz he wanted to get rid of his air-HS - now hes got 39c on idle on a raped-out XP-1700+ and only sound coming from harddrives and low-noise PSU - i think it pretty much does the job for him. Plug and play simply.
I don't understand why ppl here are so hard on this particular end-user product, it really can't be compared to anything else than a 'end-user plug/play system'