You're very welcome axsmith234,
1. 500W should be enough for everything that I've listed up there. The components that draw the most power are the CPU and GPU. You should be able to calculate an estimate using an online PSU calculator (no guarantees though). It would be wise to buy a larger power supply than recommended just for safety's sake.
http://extreme.outervision.com/psucalculatorlite.jsp
2. The Intel is faster than the X4 in just about every way.
- The only benefit of getting the AMD is the true quad-core architecture (whereas the i3 is a dual-core with hyperthreading... still good though). This will provide some performance increase with heavy multitasking or heavily threaded applications.
- The second benefit of the Phenom II is that it is a black edition processor. This means the multiplier is unlocked and will help you overclock much easier (especially if you're just starting). The Intel i3 does not offer this feature; only the processors ending with 'K' suffix do (ie. i5-2500K).
This being said, for pure best performance/price... I would just get the Intel since you would have to purchase an aftermarket cooler for the AMD. Also, the AMD AM3 motherboard is NOT high-end... I am not sure how well it will support overclocking.
3. I don't suggest you downgrade to 4GB. RAM is so cheap that it will only cost you about $20 more for the extra 4GB. Also 8GB is kind of the standard nowadays, as most systems will typically use more than 4GB underload... 8GB will give you some extra headroom. Note: Intel requires 1.35-1.50v RAM, AMD can use 1.35v-1.65v RAM.
4. I think the 7770 performs similar to the 6850, so I would just get the 7770. It is also newer technology and also more power efficient. Again, I would suggest purchasing the most powerful GPU you can afford so you don't have to worry about upgrading.
Check out this article for good recommendations for graphics cards and how they compare with one another:
http://www.tomshardware.com/reviews/gaming-graphics-car...
5. Again, you're very welcome. Good luck with everything, glad I could help.
I know what it is like to start computers... I didn't have any help and I made a few bad purchases since I wasn't able to ask for any advice from the experts here.