I'll join in on the "get an Antec" boat. It's good stuff. There are quieter powersupplies out there, but I'd be wary. The thing is they tend not to build them, but remanufactuer them. Well this leads to some of them being dodgy.
If you want something that's not hard to find, not too expensive and fairly quiet get one of their Truepower or Smartpower lines. Of those I think the Truepower makes less noise but both are good.
If you want something that's real quiet and don't mind dropping cash on it, get a Phantom. They have no fans, and thus make no noise. ONly thing is they are ike $200 and you have to consider cooling. Most cases count on the PSU to expell heat. If doesn't have to, but if it's not going to, you'll need to design around that. Have an air guide for the CPU straight to a large fan on the back, and use a lower-power video card like an X600 or something.
Now, as for cases, small and quiet are rather contradictory. The problem is that the smaller a fan is, the more noise it makes. Also the less fans you have, the faster they must spin, and thus the more noise they make. For a quiet system the best bet is a large case, with a number of slow spinning fans form someone like SilenX or Papst. 80mms will work, 100mms are beter.
The other option is, of course, lower power. Simply lower your heat output, you need less cooling, and have less noise.
More or less it's a triad of size, noise and power. You can do well on two of them, but not really on all three. If you want a Pentium D, GeForce 7800GT, RAID 0, and so on you can have all that, and have it make less noise than you'd think, but you'll need large case for it to hold all the fans, larger heatsinks (the bigger the sink, the less airflow needed), and dampening material. If you want to pack all that in a a small box, it's doabole, but you'll need fans that could lift a 777 to keep it from overheating.
Also if you want total silence, that's doable, but be prepared to open your wallet. If numbers like $5000 don't scare you, let me know and I'll help you with options.