Sorry for taking so long to get back here...
It looks kooky--2x1.86 > 2x2.66, but the processors are 4-core jobs with a BSEL modification. You can find the BSEL mod for those processors if you search the net; the info is easy to find. What you have to do is buy them refurbished to get the low-low price (mine work perfectly for used), then get crafty with TINY bits of electric tape to cover a few contacts on the bottom of the processor boards.
Nothing too difficult for anyone to do. Just get the right tools to take apart the heatsinks on your processors, and get a long magnetic driver for the fan screw. Everything else is pretty easy to deal with.
Some folks that did the mod on this forum have even higher stats than I get! But, 8000+ Geekbench is way better than the 5100 I used to get. I think I had 8500 or 8600 Geekbench for this old Mac.
If you upgrade the video card, the processors, and throw in an SSD for your primary drive, you will have a computer to last for many more years. So, $400 or so and you have something pretty keen.
Hey thanks for all of the information and responding! That sounds fantastic. I will go look up the BSEL mod to see if I can deal with the tape job... and see what I can find for cheapie processors. fun fall project!