Midrange Gaming PC For Around $1500 -- Your Thoughts?

Let me first state that while this is my second time building a PC, this is my first time *choosing parts* for a PC I'll be building. I'm a noob to homebuilt rigs. Help me out, if you could.


Case:

Antec 1200 (possibly 900)

Motherboard:

Asus Striker II NSE Core 2 Extreme/ nForce 790i SLI/ DDR3/ 3-Way SLI/ A&2GbE/ ATXMBoard

-- can I do better than this? I'd like to have the option to SLI in the future.

Processor:

Intel Core 2 Quad Q9550 2.83GHz 12M Quad Core 1333MHz Socket LGA 775

Memory:

*Probably*: Corsair Dual Channel 4096MB PC12800 (DDR 3) (this may be too expensive, thoughts? I don't want to waste money, but I don't want to buy poor quality memory either.)

Video Card:

MSI nVidia GeForce GTX 260 OC 896MB 2DVI/HDCP PCI-Express Video Card

-- would a 9800gtx be a better choice, possibly 2 in sli? It seems that for the money the 260 is the best choice right now.

Hard Drive:

I had *considered* two of these in a raid 0 for this:

Western Digital VelociRaptor WD1500HLFS 150GB SATA 10k rpm 16MB Hard Drive

Yes, I know that would probably be too expensive, so I decided to go with something like this (possibly 2):

Western Digital Caviar GP 1TB IntelliPower Serial ATA-300 Hard Drive (on sale for $99 at my uber sweetness computer store nearby)

Monitor:

I know nothing about monitors. I've used the same 17inch CRT for like 9 years, haha. I'll probably get something like this:

Samsung - 19" Widescreen Flat-Panel LCD Monitor

For around $100.

Operation System:

I'd actually love your input on this. I know XP is capped on RAM and Vista can't run old games ... which makes it difficult. I might do a dual boot, except I think that may be more trouble (and more expense -- I don't own an extra legit copy of any system atm and I want to change that for at least one) than it's worth. Honestly, the only old games I'd probably want to run on Vista are Warcraft 3 and the Fallout Series ... meh.

Power Supply:

I don't have any idea what my system will draw, but I thought I'd get something good quality that would last me a while. I don't know crap about psu's, though, so I can use any help you can offer. Something like:

PC Power and Cooling PPCT860 800W SLI Active Power Supply

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So, thoughts? I know I'm probably breaking my budget just a little bit on this, especially now that I've edited it to add power supply and monitor, so please evaluate based on performance and potential issues rather than just price. Thanks!