Not sure how big of a power supply I need

Hey all,

I'm in the process of building a computer for the first time. I'm trying to figure out which size power supply I need and I used a power supply calculator but i'm still unsure. The power supply calculator told me I could expect my system to run at 671w but this sounds high. I'm right now thinking about a corsair 750w power supply from newegg but i think this may be overkill and I was also considering a 700w cooler master PSU. Could anyone give me any advice on what size PSU to use I listed below what my system build (I think I have everything) will be any help is really appreciated.

COOLER MASTER Storm Scout
Western Digital Caviar Blue 640GB HDD
EVGA 896-P3-1257-AR GeForce GTX 260 Core 216 Superclocked Edition 896MB 448-bit GDDR3 PCI Express 2.0 x16 HDCP ReadySLI
CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready
OCZ XMP Ready Series 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800)
ASUS P6T Deluxe V2 Motherboard
Intel Core I7 920 2.66 ghz processor

The PSU calculator gives you a wattage reccomendation for a psu that will run your components ( with plenty of overhead built in ) , not the actual power consumption.
The Corsair 750 is a good choice, the 650 should work fine as well.