I'm going to go ahead and do what I could ostensibly consider to be the "smart" thing to do and just ask all of you in advance what I should buy.

I need three things:

1. CPU (AMD socket AM3). Needs to be socket AM3 because I don't feel like buying a new motherboard.
2. Video card (I don't really care what brand it is)
3. RAM (I know this really isn't difficult, but whatever)

Budget: <$400

Bonus points to the first person who suggests a bulldozer CPU.

My current system is as follows:

Gigabyte GA-770T-USB3
AMD Phenom II X2 550 3.10GHz
4.0GB of some random ram
ATi Radeon HD 5670 1GB

I just built a new one.

Case: Antec p280
Mobo: Asus p8z68-v Pro/Gen3
CPU: Intel i5 2500k
RAM: GSKILL 4x2 8gb 1600 DDR3
Video: SAPPHIRE AMD Radeon HD 6870 1GB
SSD: Crucial M4 CT128M4SSD2 2.5" 128GB
Power: Antec Truepower New 23652 TP-650 650-Watt

And my old blu-ray drive.

Alright well I'm going to take the advice that CM gave in the chat and go with this card:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814102954

Against his claims that I don't need to, I think I'm still going to buy an assload of ram.

Here are my thoughts:

CPU: Your motherboard supports ACC and core unlocking. Have you tried 'unlocking' your current X2 550 to see if it unlocks to an X4? Personally I have never been successful with this but your motherboard manual should be able provide some insight on how. Look for a BIOS setting called ACC. I'm don't think any upgrade beyond a PhenomII X4 is 'worth it' if your primary uses are casual websurfing/gaming. Most games wont take advantage of >4 cores yet. If your current chip refuses to unlock, I think the best bet for an upgrade is the PhenomII X4 960T. It's based off the lastest Thuban (x6) core, it's multiplier unlocked which makes overclocking really simple, and also has a chance of unlocking to a X6. Typical price: $125

Videocard: If better gaming performance is your goal, this should be where most of your budget is spent. For $200 you should be able to get a 6870 or GTX560 (possibly GTX560TI) pretty easily. Look for dual fan models if keeping noise low is important to you. If you do spend more of your budget on CPU or RAM, there are some reliable sites that offer Refurbished videocards like newegg.com/geeks.com/evga.com. I've seen refurb 5870's and 6870's for ~ $130.

Ram: It's still very cheap right now. Dunno if it's worth trying to find a matching kit for your existing 4gb (is it DDR3-1333, 1600? what timings?). Or just get another 8gb kit which can be found for ~$40 without any special deals.

Thats a good choice, although I'm guessing that wont be one of the 6950 2gb that can unlock to a 6970 because it's not a reference design. Still a beast of a card.