A few things before purchase...
With the CPU, the FX-8120 is actually the same processor as the FX-8150, but at a lower clock and price. You can buy the 8120 and OC it up to 8150 levels to save a bit of cash.
With coolers, you don't need something super expensive unless you are doing some serious overclocking. I use a XIGMATEK Gaia SD1283
, well, another Xigmatek product which shares the same design anyway. It keeps things cool and quiet. However, keep in mind that regardless of whichever CPU cooler you use, that HDT coolers require a different thermal compound application method to be most effective. The standard "dot in the middle" will give you increased temps with HDT. Check out this
article out for more details, I used the double line method.
Windows 7 Ultimate? May I ask why? Almost all home users only need Home Premium. Professional, maybe. I use Professional as I backup over a network and that is the only thing I use Professional for. Ultimate is essentially Enterprise edition available outside of a volume license agreement. Unless you use some high-end stuff like domain-aware printing or EFS, you only really need Home Premium.
The lowest price I see for a 6850 is $135 before rebate, and that is the SAPPHIRE 100315L Radeon HD 6850 1GB
As for PSU's, I usually stick with Corsair, Silverstone, Seasonic, PC Power & Cooling, XFX, and Sparkle Computer. All are good.
If you want to squeeze every last bit of value out of these purchases, check to see if your credit card, bank, airline, hotel company, etc. has a program where you can get cash back or points for shopping at certain retailers. Your employer may also have deals with various e-tailers. Typically, to take advantage of these offers, you have to use a special link from the website offering the incentive, they will track the purchase that way.