No, it's not due to your CPU... when I reviewed the 01X for EQ magazine, one of the machines I tested it on was MY Athlon 64 3400, and it worked like a charm for me. http://www.eqmag.com/story.asp?sectioncode=39&storycode=4652
You don't want the firewire card disabled when you do the installation. Also, have you tried a different firewire card, or installing your firewire card into a different PCI slot on your motherboard? That might help.
It's been a while since I installed everything, so my memory is a bit hazy on the actual details, and I'm in the studio all weekend, so it might be a day or two before I can really check it out... and this version of this forum is going to be archived as of Monday, so I won't be able to respond here... but there will be a "NEW" Project Studio forum over here, and I'll also be moderating a new forum over on http://www.harmony-central.com
so feel free to continue the discussions on both of those sites if you would like to.
Also, have you asked for suggestions over on http://www.01Xray.com