Decisions on new gaming computer, advice needed!

[thenewpcgamer]

First off, I want to ask a quick question. Should I get a make my own desktop or should I get the Alienware M17x:
http://www.alienware.com/Landings/promotions.aspx
Tell me what you think.
If you think I should make my own, here are some details and the parts I have so far.

Approximate Purchase Date: Before 2012

Budget Range: Less than 2K (But it can go a bit over)

System Usage from Most to Least Important: Gaming>Watching Movies>Media>Audio/Video Editing

Parts Not Required: -

Preferred Website(s) for Parts: newegg.ca, but anywhere that is cheap and ships to Canada is fine

Country of Origin: Ontario, Canada

Parts Preferences: -

Overclocking: Probably not since I don't even know how to, but if you can explain to me how I might overclock

SLI or Crossfire: Yes.

Monitor Resolution: 1920x1080

Additional Comments: I'm new at building computers so I would like as much help as possible

CPU: Intel Core i5-2500K ($219.99):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16819115072

CPU Fan: Cooler Master 212 Hyper Plus ($39.99):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16835103065

Motherboard: Either the ASUS Maximus IV Extreme-Z or the ASUS Maximus IV Extreme. Would the non-Z version be too much of a downgrade? ($334.99 for Z version and $309.99 for non-Z version):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16813131760&Tpk=asus%20maximus%20iv%20extreme-z
http://www.newegg.ca/Product/Product.aspx?Item=N82E16813131700

RAM: Corsair Vengeance 8GB ($57.49):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16820233186

Video Card: Dual ASUS GTX560 TI ($499.98):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16814121425

Hard Drive: Western Digital Caviar Black 750GB 7200RPM 64MB Buffer SATA3 3.5IN ($60.35):
http://www.directcanada.com/products/?sku=1508135249P&vpn=WD7502AAEX&manufacture=WESTERN%20DIGITAL

SSD: This SSD will be for Windows 7 and such. Intel 320 Series 2.5" 80GB SATA II ($159.99)

Optical Drive: One is Blu-Ray and the other DVD Burner ($69.99 and $22.99):
http://www.newegg.ca/Product/Product.aspx?Item=N82E16827135247
http://www.newegg.ca/Product/Product.aspx?Item=N82E16827135204

Power Supply: I don't really know what wattage or power supply I should get so if you have any recommendations please tell me.

Case: Cooler Master HAF X ($164.70):
http://www.directcanada.com/products/?sku=11130AC7104&vpn=RC-942-KKN1&manufacture=COOLERMASTER

Monitor: I'm thinking about getting this one, but if you have a smaller recommendation (Since I'll be sitting right in front of it) please tell me. ($179.99)
http://www.newegg.ca/Product/Product.aspx?Item=N82E16824236059

Keyboard: Logitech G110 ($65.52)

Mouse: Logitech G500 ($59.43)
http://www.directcanada.com/products/?sku=12660ID2220&vpn=910-001260&manufacture=LOGITECH

Ok, so let me know what you think, Alienware vs custom built, and if my custom build parts are ok.
Thanks in advance

 

[cutebeans]

Hello, friend! It is better if you stick to a single stronger card like the GTX 570 or GTX 580.

It would be best to get A 750w if you really do plan to SLI.

SSD would be better if it were M4 Crucial 128gb.

 

[thenewpcgamer]

Hello, friend! It is better if you stick to a single stronger card like the GTX 570 or GTX 580.

It would be best to get A 750w if you really do plan to SLI.

SSD would be better if it were M4 Crucial 128gb.

I think I will stick with the Dual 560's, thanks for your advice, though.

I will start looking for 750w power supplies.

I'm kind-of reaching the limit of my budget so the I won't be getting the M4.

Also, as I said on my original post, should I get the ASUS Maximus IV Extreme-Z motherboard or the non-Z version?

 

[cutebeans]

If you look at the features and specs, The z version has nothing big over the non z

 

[thenewpcgamer]

If you look at the features and specs, The z version has nothing big over the non z

Ok, thanks, I will get the non-Z version if I go by building my own desktop.