couple things to look for in a power supply...
modular ones are great because you can use only the wires/connectors you need (helps air flow & reduces clutter)
if it has the new 6-pin connectors specifically for pci-e graphic cards thats great. otherwise pci-e cards will use a y-harness to connect to two molex wires.
if quiet is a priority the most recommended is seasonic S12 series (they been around a long time) or antec neo psu's.
efficiency - look for psu's approved by the 80 plus program
. effecient psu's make for less heat less noise and smaller electric bills.