Here are some reviews of various levels of PSU that should help inform you a little more. When purchasing somehting as sensitive as a PSU it is always best to do some research.
Midrange
http://techreport.com/reviews/2004q4/psus/index.x?pg=1
http://www.xbitlabs.com/articles/other/display/atx-psu4.html
Highend
http://www.bytesizedreviews.com/?rev_id=302
Really Highend
http://www.legionhardware.com/document.php?id=574
Here are some good PSUs that should do fine powering your rig:
SeaSonic S12-500 ATX12V 500W Power Supply ($129)
http://www.newegg.com/Product/Product.asp?Item=N82E16817151024
dual 12v rail with good amps (17, 16 amps), excellent rep, Active PFC
SILVERSTONE SST-ST50EF ATX12V 500W ($89)
http://www.newegg.com/Product/Product.asp?Item=N82E16817256001
dual 12v rails, strong amps (18 per rail), excellent rep, Active PFC
Thermaltake W0057RU-01 PurePower TWV ATX 12V 2.0 500W ($129)
http://www.newegg.com/Product/Product.asp?Item=N82E16817153031
dual 12v rail with good amps (18 amps per rail), excellent rep, Active PFC
ENERMAX Liberty ELT500AWT ATX12V 500W ($105)
http://www.newegg.com/Product/Product.asp?Item=N82E16817194003
dual 12v rail with STRONG amps (22amps per rail), excellent rep, Active PFC
XCLIO X14S4P3 500W ATX 500W ($95)
http://www.newegg.com/Product/Product.asp?Item=N82E16817189012
triple 12v rails (18, 18, 16 amps), modular, Active PFC, Good Rep
ENERMAX Noisetaker II EG495P-VE ATX12V 485W ($90)
http://www.newegg.com/Product/Product.asp?Item=N82E16817194009
dual 12v rails, strong amps (22 per rail), excellent rep, Active PFC
FSP Group (Fortron Source) AX500-A, 2.0 version, 2 SATA, PCI Express, 500W ($90)
http://www.newegg.com/Product/Product.asp?Item=N82E16817104934
dual 12v rails, amps are ok (15 amps per rail), excellent rep, Passive PFC