well using a 333 chipset such as the KT333 does allow you to run at 166/166 with no problems, as the chipset was designed in this way. So providing you have 333 memory, the only problem lies in the processor.
If i was to upgrade my memory to PC2700 I would definitely try for the 166 outta my XP1800, and im sure with good cooling it would be acheiveable. I mean my old Duron could be pushed upto 145 fsb and thats with a KT133
