Comments/Suggestions on my project

So, I decided to build a rig... It is just for fun and learning about bitcoin mining.

Here's what's on order:
- TJ11-BW (Black) case
- MB MSI 890FXA-GD70 AM3 R
- Lian Li Dual Power Supply Adapter Cable
- SILVERSTONE ST1500 1500W ATX12V/EPS12V SLI Ready CrossFire Ready 80 PLUS Silver (2 of these) (for attempting to run 5-6 6990s later)
- 64GB Crucial m4 2.5-inch SATA 6GB/s
- 8GB Kit (4GBx2), Ballistix 240-pin DIMM Upgrade for a MSI (Micro Star) 890FXA-GD70 System
- XFX ATI Radeon HD5830 1 GB (ordered 6)
- AMD Phenom II X2 555 Black Edition Callisto 3.2 GHz
- Cooler Master RR-910-HTX3-G1
- I'll get some fans at a store once I see how this all fits together...
- will get some PCIe x16 cable extenders as needed

I'm thinking of loading win7 64bit on half the drive, and then loading ubuntu on another 8GB partition and have some more room for other OS'es to experiment with. Ofcourse, booting from USBs for other OS flavors is always an option if the drive gets full.

My goal is to have 5-6 6990 running whenever they become available (perhaps a few months later) if this is possible.

I will stay away from crossfire and will just plugin dummy plugs (this should cover all OS'es). Will probably flash the video BIOS after I find a comfortable and stable OC combination on the 5830s and other cards.

Do you think I should consider anything else? Willing to try/experiment if there are good ideas out there...

What do you think will give me trouble and how did you solve it?

Will try to provide updates on my project so that others can benefit from my experience with this...

Thanks!