AMD/ATI Crossfire Phenom II X4 955 M4A79 Deluxe

I think I'll have enough money to build (my first) a new gaming and multitasking PC by September (October at the latest), and I was just doing some early research into what I would buy. My first question is, how much will AMD/ATI's product lines change between now and then, and how much will prices drop? I'm not going to buy the parts on credit because that is an option I will not pursue, so I have to wait until I have sufficient funds. Will what I've picked out so far be sufficient and still in stock? Or will I need to redesign the build? If the prices are lower, would it be better to pay for what I've picked out, or to pay slightly more for slightly newer parts? Of course, to answer those questions, you'll need to know what I've all ready found that I like.

Processor

AMD Phenom II X4 955 Black Edition Deneb 3.2GHz 4 x 512KB L2 Cache 6MB L3 Cache Socket AM3 125W Quad-Core Processor

Motherboard

ASUS M4A79 Deluxe Motherboard - AMD 790FX, Socket AM3, ATX, Audio, CrossFireX, PCI Express 2.0, Gigabit LAN, USB 2.0, SATA, RAID

Edit: I'll probably go with the MSI 790FX-GD70 AM3 AMD 790FX ATX AMD Motherboard
Which is even better because you can purchase it in a bundle discount with the Phenom II X4 955 Black Edition Deneb Processor.

Memory

TWO of Patriot Viper 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Dual Channel Kit Desktop Memory Model PVS34G1333LLKN

GPUs

TWO of VisionTek 900250 Radeon HD 4870 X2 2GB 512-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card

Case

GIGABYTE 3D Mercury Pro GZ-FW1CA-AJB Black Aluminum ATX Full Tower Computer Case

Hard Disk

Western Digital VelociRaptor WD1500HLFS 150GB 10000 RPM 16MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive

Operating System

Microsoft Windows Vista Home Basic SP1 64-bit for System Builders

PSU

XCLIO STABLEPOWER 1000W 1000W ATX SLI Ready CrossFire Ready Active PFC Power Supply

CD/DVD Burner

Pioneer Black Qflix 20X DVD+R 8X DVD+RW 12X DVD+R DL 20X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 40X CD-R 32X CD-RW 40X CD-ROM 2MB Cache SATA 20X DVD±R Burner

And I'm thinking about using a sound card over the motherboard's onboard audio.

HT | OMEGA CLARO Plus+ 7.1 Channels 24-bit 192KHz PCI Interface Sound Card

So my main questions are:

1) Is it a valid build? Will all components work together?
2) What is the overclockability of the system?
3) Will the liquid cooling system and fans in the case be sufficient to cool the system? If it is overclocked?
4) Would you recommend any additional or alternative components? Why?
5) Is an OEM system-builder OS the right thing to purchase? I know there are some peculiarities about it. (One of which I think is that you can only put the OS on the computer you build.) I would buy the retail version, but I understand that you have to pay $11 dollars for Microsoft to send you an upgrade CD/DVD to get the 64-bit OS.
6) Am I getting the right memory frequency/speed? I read up on this article DDR3 Memory Scaling On AMD's Phenom II X4, and it said that there isn't really much of a difference in performance between DDR3 1333 and 1600. I think there were even a few instances where 1333 performed better.
7) Should I just buy enough to build a working system and wait to purchase the second GPU, second memory kit, and audio card?
8) Anything else that I haven't thought of yet?

1/ I know that most people recommend about 2GB of memory for a computer. However, the RAM is cheap enough. Of course, it's foolish to buy something only because it's cheap. I do have reasons for getting the RAM other than just blindly assuming that more is better. My understanding is that more RAM helps multitasking apps and reduces the delay between switching apps. That's one reason I'm going to get the RAM. The second reason is that some games cache data such as textures and maps into memory for faster access. If you know how to alter settings to get the games that can do this to keep more data loaded, then the extra RAM can be useful.

2/ Obviously I'm not going to be overclocking to >5 GHz as seen here, but I'll give it a go. I wasn't asking how to overclock, I was asking how well the system would overclock.

Edit: I changed my mind. The more I think about potentially decreasing the lifespan of components, the less interested I become in overclocking. I don't want to have to buy new components too often. At most, I'd probably only get a ten frame increase in FPS in games by overclocking both the CPU and GPUs. If a couple of years down the road there is a game I really want to play but requires a little better than what I have, I'll overclock then.

3/ I'm definitely interested in playing the latest games in high-resolution and with anti-aliasing. I'll definitely be getting a nice high-res monitor.

4/ I'm looking at the Windows 7 rc page now.

5/ I'll definitely look over prices and components again and post here again.