Help buliding system around good video card

Few questions to start off...
I'm supposing your not going to 939 because you already have DDR memory?
As well, do you plan on keeping this system for a good amount of time? The X2 3800 is not that much more expensive and will last you a little longer than the 3400+. As for the PSU and heatsink... For the PSU there are multiple recommendations I can make, OCZ, Fortron, Enermax, Seasonic or Antec are all good brands. Are you planning on OC'ing? The stock heatsink will work fine if your not.

I do have DDR and can upgrade that if it's worthwhile. I plan on keeping this sytem for 2 years. I do not plan on OCing.

I suppose if your buying a x1950 your probably dabbling in a little gaming? As for the processor, I'd suggest just getting a retail X2 3800+ for the minimum. If you want this system to last you two years then you probably want to consider dual-core. As of right now, the performance increase to dual-core from single core is not that great. However, I assume sometime within the next two years, programs will be optimized for dual-core cpu's so it's good to have at least that. Other than that if you need help picking out a PSU just ask or post a link to one that you've chosen (reading reviews is always best way of choosing).
http://www.newegg.com/Product/Product.asp?Item=N82E1681...
That's the cheapest retail dual-core 939 I found on Newegg, however if your looking for something cheaper, I'm sure you could find an X2 3800+ elsewhere.

alright, updated with what I think is compatible:

AMD Athlon 64 X2 4200+ Manchester 2.2GHz 2 x 512KB L2 Cache Socket 939 Dual Core Processor - Retail
$200 http://www.newegg.com/Product/Product.asp?Item=N82E16819103547

ASUS A8N5X Socket 939 NVIDIA nForce4 ATX AMD Motherboard - Retail
$75 http://www.newegg.com/Product/Product.asp?Item=N82E16813131569

PNY Optima 1GB (2 x 512MB) 240-Pin DDR2 SDRAM DDR2 533 (PC2 4200) Dual Channel Kit Desktop Memory - Retail
$100 http://www.newegg.com/Product/Product.asp?Item=N82E16820236102

ATI 100-437807 Radeon X1950PRO 256MB 256-bit GDDR3 VIVO PCI Express x16 CrossFire Video Card
$275 http://www.newegg.com/Product/Product.asp?Item=N82E16814195029

Rosewill RP550-2 ATX 2.01 550W Power Supply 115/230 V CSA, CB, TUV, FCC, UL - Retail
$50 http://www.newegg.com/Product/Product.asp?Item=N82E16817182017

ARCTIC COOLING Freezer 64 Pro Cooling Fan with Heatsink - Retail
$15 http://www.newegg.com/Product/Product.asp?Item=N82E16835185125

save yourself 75 bucks and go with the sapphire version

http://www.newegg.com/Product/Product.asp?Item=N82E16814102061

or $110 and get the asus version

http://www.newegg.com/Product/Product.asp?Item=N82E16814121031

First of all, you don't need the AC Fan if your getting the retail box. Is there any reason you wanted a fan other than that of the retail AMD one?

Asus A8N-E Mobo
Asus A8N-E $78, not much more expensive, but a better motherboard IMO.

As for the memory, I thought you already had some? What do you have right now? If you don't have memory already then we'll discuss that.

apt403 is right, go with the sapphire version of that video card. Here's the link:Sapphire x1950pro

FSP Blue Storm 500W PSU
Much better PSU for only a little bit more.

Awesome. Thanks for the help - I don't want to be stuck with something that's not going to work. I may or may not need to get new memory - have to head home & figure out what's in my broken system.

I like this list, but i could make a few slight changes:

1st, the x1950pro. Save 70 and get the Sapphire version. No reason to pay more when everything except the cooler and decal are the only things different between the two.
Powersupply wise: Don't exactly know the reliablity Rosewill has on power supplies, but i would go with something a little more expensive. Never Ever skimp out on a powersupply, or it could end up taking more parts than you bargain for if anything should happen to it.
This looks appealing:

http://www.newegg.com/Product/Product.asp?Item=N82E1681...

Memory wise: If your ram hasnt gone with the motherboard, use that, and buy the extra 1gig of ram coops recommended. If you have 2 gigs, and both sticks didnt fry, then dont bother with extra ram. If all the sticks did in fact go, purchase 2 sets of the 1GB from PNY. 2Gigs is recommended for heavy gaming.

Hope everything goes well.  

Even though the X1950Pro is sold out, I'd wait for it to come back in-stock and not get the ATI version.

Zipzoomfly does have the ASUS X1950Pro in-stock but for the same price they are not including VIVO if that matters to you. Newegg did have this version of the card for $171 including shipping. Now, to save 30 bucks if you don't need VIVO would of been worth it.