My antec 900 rig :D

Originally Posted by Big B

A single 18A +12V rail is fine for Socket A and Socket 478 Pentium systems with AGP. If you're running PCIe, the bare minimum you should look at would provide 25A, but ideally at least 30A.

Antec, Corsair, Seasonic, Thermaltake (specifically the Toughpower line), Enermax, FSP/Fortron/Sparkle, XClio, Silverstone, OCZ, PC Power & Cooling...those are brands you're gonna look at.

As already mentioned, don't go cheap on your power supply. That's the starting point of your components health and stability, so it's not the place to skimp.

The Corsair VX 450 and 550, TX650 or HX520/620 are some excellent units, and usually run around $100 or less here in the US. The HX units are modular, so you can remove cabling you don't use. That's something to consider to help keep your cabling neater.