Hey dude, this is the Intel Motherboard forum!
But, in any event, here's some observations:
1. You're not gonna run that 1 GHz T-Bird at 1.67 GHz anyway. Maybe 1.33 GHz is possible if you simply set the FSB at 133 MHz.
2. None of the reviewers I've seen have been able to run the FSB over 140 MHz on this board. So forget setting the FSB at 166 MHz.