Totally agree on the better power supply. Yes it cost more but you are much better off in the long run. 500W is too little for a modern system let alone a gaming system.
DDR3 only. Besides you wouldn't want to throw in an odd number of sticks and lose dual channel mode and decrease the performance of the ram.
Windows 7 will work just fine on your system. The "works with windows vista (or whatever)" thing really doesn't mean anything. It simply states that it was tested with vista and they paid their money to M$ to get the insignia. When it comes to the operating system the important thing is to make sure that all your drivers are available. Which that shouldn't be an issue, pretty much everyone has drivers for 7 now. Well all the major components do anyway.
30 minutes I do believe.
You can edit your posts up to after an hour (or 30 minutes), I can't remember which.
8 Pro 64bit
AMD FX 8350
Asus Sabertooth 990FX R2.0
16GB G.Skill Sniper 1866MHz
OCZ Vertex 4 128GB SSD
HDD's 3TB/2x 750GB/500GB/250GB
2x XFX 6870 1GB
PC P&C 750W PSU
Cooler Master HAF 932 Red LED
CM Hyper 212 EVO w/2x SickleFlow 120mm Red LED
Logitech X540 5.1 Surround
2X Acer 23" LED - Eyefinity: 3840x1080
"The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
- Albert Einstein