Build- Budget gaming system with room to grow.

Hi. Im looking into buying parts to build a pretty decent system that several parts that will be future proof for a few years. After doing a little research Ive decided to go with AMD. I kinda have a budget of $1000, can go over a little. The way I plan on buying the pieces is basically piece by piece. This week Im buying the case and PSU. Next week the motherboard, the following memory and harddrive... etc. In all this should take around 1-1/2 months. The only thing set in stone is that Im plan on getting 1 Radeon 5850 now and another at some point later next year(using Crossfire). FYI, last time I did a build was back in '98, been away since then.

Heres the required info.

APPROXIMATE PURCHASE DATE: Starting now, ending sometime around late nov, early dec.

BUDGET RANGE: Around $1000, can go up a little but not too much

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: Gaming, streaming movies, school work

PARTS NOT REQUIRED: None, Im starting from scratch, but not going to list small items such as keyboard, dvd/cd drive, mouse, pc speakers.. etc. Just going to stick with the major components.

PREFERRED WEBSITE(S) FOR PARTS: Newegg or microcenter(I have one not too far).. can go with others for good deals

COUNTRY OF ORIGIN: USA

PARTS PREFERENCES: None, other than sticking with AMD

OVERCLOCKING: Maybe

SLI OR CROSSFIRE: Yes- Crossfire in the near future

MONITOR RESOLUTION: Plan on going 1680x1050, 1920x1080, 1920x1200. Would like to use my tv sometimes if possible so I can play a game comfortably on the couch.

ADDITIONAL COMMENTS: Quiet would be nice

This is what Ive sorta came up with... Would love some feedback.. good or bad..

Case: $50
Rosewill R5601-BK
http://www.newegg.com/Product/Prod [...] 6811147038
Definatly getting this one this week, had good reviews and is priced right.

Graphics Card: $260
SAPPHIRE 100282SR Radeon HD 5850
http://www.newegg.com/Product/Prod [...] 6814102857
Not going with the 5870 because the specs for this is already amazing, and since I plan on getting another one a bit later.

Processor: $102
AMD Phenom II X2 550 Black Edition Callisto 3.1GHz
http://www.newegg.com/Product/Prod [...] 6819103680
I know there are better out there, but I chose this processor because I wanted something AM3, but not too expensive. I was pleasantly surprised that you could unlock the 2 other cores which makes this a GREAT deal

MoBo: ?
This is where I need some help. I need a board that can support up to 2 Radeon 5850 for Crossfire(that means 2 PCI express x16), would like to take advantage of NOT getting DDR3(That means no AM3 only boards) right now since the price for DDR2 is soo much cheaper. So Im basically looking for a AM3/AM2 board.

PSU:$119 - 109 after rebate
CORSAIR CMPSU-750TX
http://www.newegg.com/Product/Prod [...] 6817139006
Going 750 because: I want to be able to use this for a future build; I am going to Crossfire; the price of it is only $10 more than the 550 sister and is a great deal right now.

Memory: 70-80
There are so many to choose from. Looking to spend 70-80 and getting 2 x 2gb right now and adding another 2 x 2gb when needed in the future.

Sound Card:
None, Using onboard sound.

Harddrive: ?
Decided to go with a 500GB and not a 1TB. I dont have allot to store and usually only have 2-3 games stored on my HD. Lets just say Im the kind of guy thats content with my 8gb nano and have no need for a 120gb monster. The question I do have is if the 7200rpm is worth it? Will there be THAT big of a difference if I only go with a 5900 to save a few dollars.. Looking for price/preformance.

Monitor: Not sure if its possible, but can you use an lcd tv for heavy gaming. I have a 50" in my living room. I can set up my laptop right now and watch movies on there with no problems, but are the refresh rates on the tv enough? Think thats the question I was looking for, dont really know too much about it. Other than that, will probably pick up a 22"(for normal use) on sale somewhere for around 150(hopefully) or will probably wait until Black Friday and pick one up cheap somewhere.

Yea, your right... after thinking about it decided to go with ddr3.
G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600
http://www.newegg.com/Product/Prod [...] 6820231193

Still like the Cosair PSU better since it already has Crossfire adapters built in and I dont mind it not being modular. And O yea, and for cooling Im going with:
ARCTIC COOLING Freezer 7 Pro Rev.2 92mm Fluid Dynamic CPU Cooler - Retail
http://www.newegg.com/Product/Prod [...] 6835186134

Good idea with the Samsung Spinpoint.. added that to my list

So Im kinda torn between these 2 mobo's...

ASUS Crosshair III Formula AM3 AMD 790FX ATX AMD Motherboard - Retail
http://www.newegg.com/Product/Prod [...] 6813131392

and

MSI 790FX-GD70 AM3 AMD 790FX ATX AMD Motherboard - Retail
http://www.newegg.com/Product/Prod [...] 6813130223


Anyone have opinions about them? One is significantly cheaper than the other and both have good reviews. Should I go with the cheaper one?