Hi everyone! I think I posted in the wrong area before so I am moving it here now that I know a little more. First thank you for all of your help so far! I think I was getting in over my head a little bit. So basically my old computer broke down and well here is what I have left:
---I have the case (my old computer was ATX)
---ALLIED AL-A400ATX power supply
---Hard drives

OK now from your advice here is what I am thinking about:

--Mother board = ASUS A8N5X Socket 939 NVIDIA nForce4 ATX AMD

--Video card = eVGA 256-P2-N386-AX Geforce 6800GS 256MB GDDR3 PCI Express x16

--Power Supply = Thermaltake TR2 W0070 ATX 430W

--RAM = G.SKILL 2GB (2 x 1GB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Unbuffered System Memory Model F1-3200PHU2-2GBNS

--Processor = AMD Athlon 64 3700+ San Diego 1GHz FSB Socket 939 Processor Model ADA3700BNBOX

So after all that I have 3 final questions if you guys can help me out again!
1) Do I really need a new power supply? Mine was working fine before but if you think its a good idea, I will buy one.

2) Do I need to buy a fan or heatsink or the paste or those things?

3) What I guess I am wondering is, will this work?? lol, I mean will those parts work with each other?

Thank you guys so much for your help, I am buying these things from that New egg site based pretty much solely on your recommendations so if you think I am making a mistake let me know! I want all of your feedback, you seem like a very nice group of people here so I think I will like being here! Thanks again! -Ashleymom