What size PSU would you recommend for this build?

[wailord]

CPU
Intel Core 2 Quad Q9550 2.83GHz, 12MB Cache, 1333MHz FSB, Yorkfield, Quad-Core, Socket 775
(may overclock slightly)

RAM
4GB Corsair XMS2 TWIN2X 4096MB PC8500 Memory - DDR2 1066MHz Dual Channel (2x2048) CL5
(may upgrade to 8GB in the future)

MoBo
XFX nForce 750i SLI Extreme Motherboard - NVIDIA nForce 750i, 45nm Support, Socket 775, RAID

Video Card
GeForce 9800 GTX + Video Card - 512MB GDDR3, PCI Express 2.0
(may upgrade to 2 in SLI, just one for now)

HDD
WD VelociRaptor 150GB SATA HD 10K/16MB/SATA-3
(may upgrade to 2 in RAID 0)

1 optical drive

I am thinking 750watts will be sufficient based on adding up each of the components power usage, but do you think I should go for more? I am worried if I do eventually upgrade my RAM, put an extra video card in SLI, extra hdd in RAID, and overclock the cpu I will be short on power.
So should I go for an 800/850/1000 watt upgrade any recommendations? thanks in advance

 

[JohnnyLucky]

The general rule of thumb is a high quality 500 to 500 watt power supply with sufficient current (amps) on the 12 volt rail(s) can easily power a system with any single video card made. A high quality 700 to 750 watt power supply with sufficient current (amps) on the 12 volt rail(s) can power a system with two video cards operating in dual mode. There are a few exceptions like the new ATI Radeon HD 5XXX series cards which use less power due to their energy efficiency.

Before purchasing a new psu you will need to decide whether you will eventually have a pc with one or two video cards.

Corsair, PC Power & Cooling, and Seasonic are some of the brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Lately we've been seeing a few other brands offering some high quality units.