I'm building a gaming pc with the following:
Intel Core i7-2600 Sandy Bridge 3.4GHz Quad Core

ASRock B75M-GL LGA 1155 Intel B75 SATA 6Gb/s USB 3.0 Micro ATX Intel Motherboard



CORSAIR Vengeance 8GB (2 x 4GB) 240-Pin DDR3

EVGA SuperClocked GTX 660 Ti 2GB 192-bit GDDR5 PCI Express 3.0 x16

Western Digital Caviar 1TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5

I need to know how powerful my power supply needs to be.

thanks, bros.

http://extreme.outervision.com/psucalculatorlite.jsp

This calculator is quite detailed.