Whoa, where to start.
First off, bad choice on the CPU, if your looking for dual core, your going for an AMD x2 series, they blow intel away in every test, even their lower end CPU blows away Intels highest priced processor.
This means your going to have to get a different motherboard, if you are going t overclock, and go with two graphics cards, first off I recommend:
You go with Nvidia's SLI system, they currently have theb est cards on the market.
You get ddr400 ram, pc3200.
The motherboard you should choose is an ASUS SLI board.
A few other pointers, graphics card brands, evga, leadtek, msi, bfg, those ones. Your hard drive should be SATA and you should get seagate brand, they have good warranties and they are a really good brand. If your overclocking, you might want to go with some OCZ or g.skill ram.
I'll leave it up to you on what parts you want to pick out from here.