Need CPU upgrading advice

Hey guys,

I need some advice.

I am upgrading my computer part by part. I just bought a 8800gts and want to upgrade my cpu in the coming months.

I have a socket 939 mobo and I wanted to move into dual core without switching to AM2 sockets.

2 years ago I bought the AMD FX-55 ClawHammer for $800:
http://www.tomshardware.com/2004/10/19/amd/page5.html

Today I was looking at the AMD Opteron 185 Denmark:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

How much of a difference am I going to see if I get this dual core proc? I am mainly a gamer and also a 3D modeler that uses Maya and After Effects a lot.

If you have any other AMD procs in mind let me know.

Thanks for the help!