Switch from dual processor system?

Hey guys, just need some help here with regards to my current setup. I bought a computer that I used for work recently and it's a great system. it was originally purchased for me in 2005 when there weren't a lot of dual core processors around. Its a dual processor workstation that currently has the following configuration:

Tyan 2895 Mobo Dual Socket 940(Awesome motherboard capable of handling dual core chips as well)
2 x opteron 246's 2.0 ghz
2 gb ram

Here is the thing, I am thinking about upgrading this machine however, cpu speeds and options have come around so fast now that I can possibly do my work (3d graphics and rendering) using a regular dual-core, single socket motherboard setup. I need some advice whether I should try and sell this setup now and go for the single socket setup or should I keep the current config and possibly just upgrade the chips as the come out?

There are a few things that I have considered. If I upgrade to a single socket, I will get an intel setup which seems to have quite a long future ahead of it seeing as how the board I would get would be capable of accepting quad core chips. Does the opteron have an extended future plan or is AMD stopping the 940 socket for something else coming up? I have not seen much advances in terms of the speeds one can get from the socket 940's for a little while and that has me a little worried about future viability for my dual processor setup. granted though, if I can use a quad core setup sometime in the future with this motherboard, how long will it take for applications to be able to use this power?

Right now upgrading the dual processor setup will be more expensive in the future than that of a single processor motherboard. that has me worried as well as the fact that opteron processor costs have not really dropped all that much.

take care guys.