SPCR, google it.
Lots of tips and reviews of quiet stuff in there.
It's tricky to measure noise. but I can give some input...
I've always used Antec P180/P193 cases and they're near enough silent with tricool fans on low.
I've always replaced the stock Intel cooler with an Arctic Cooling Freezer 7 pro, which is near enough silent.
I'm current running a Sapphire 5870 Vapor-X (which I believe they renamed), and that's near enough silent too. I think the Phantom nvidia models are similar.
I've always used Antec TruePower PSUs, never heard a peep out of it - odd to believe some ppl complain about their PSU noise.
That's true, I've always described my rig as "near silent". Meaning I can't hear it as long as I'm not trying to.
My mates said the same, I went round their place and it's an offensive racket!