Question : Problem: Upgrading CPU - Athlon 3500+ to Opteron 185?

My current desktop is a bit over two years old, running an AMD 3500+, Epox 9NPA nForce Ultra mobo, 2GB Corsair XMS RAM, Nvidia GeForce 6800 Ultra.  I use it mainly for gaming and have shifted most of my web design, photo editing, and generally all of my work material over to a new MacBook Pro that I just bought; now I'm trying to decide whether to upgrade this current machine and keep it around for a while longer or build a new PC all together.

I was thinking about upgrading the 3500+ that I have to an Opteron 185.  Yes, it's a server processor (and can't find any relevant benchmarks) but it would be a pretty big upgrade over what I currently have.  I've heard nothing but good stuff about it from people that have bought it, and obviously it can't compare to a Core 2 Duo but whenever I DO build a new PC, this one will be turned into a server so the Opteron would definitely come in handy there.

But not being able to find any real documentation on performance, would it be worth it to spend the ~$200 on this to hold be over for a bit until I can throw together a new system, or should I hold off and just deal with the old hardware a bit longer?  I've thought about grabbing a new video card while I'm at it and that would hold me over even longer from building a new PC, but I'm still torn.

Answer : Problem: Upgrading CPU - Athlon 3500+ to Opteron 185?

If you're going to build it like a server, it's going to sound like one. Although the Opteron isn't supported for this board, it is being used on them. The Bios needs to be upgraded but the cool'n quit software in the bios doesn't work with the Opteron. Be prepared for lots of fan noise.

Here is a CPU chart which shows the Passmark benchmark results for a number of CPU's including the Opteron.
 
Opteron 185--> passmark score 1121
http://www.cpubenchmark.net/high_end_cpus.html
The AMD Athlon 64 3500+  --> passmark score 444
http://www.cpubenchmark.net/mid_range_cpus.html