Apparently Don hasn't played with an Intel Duo core iMac. I have one with XP in a dual boot configuration. Mac OS 10.5 loads from off to full operate in just under 30 seconds. The XP boot takes nearly 5 minutes.
I suspect you don't have the latest version of Echomac. You might want to look here: http://echomac.sourceforge.net/
This is the fat version, but I don't think that's the problem.
If you still can't get it to work, e-mail them. I've been told there's a Yahoo group too, but I've never looked for it.