I think if you follow simp's guide word for word, (i.e. set 266/333 NB strap, with 333 apparently being the most stable for high fsb) that's what haes ended up with. I took a close look at his settings though and thought I need to drop quite a few voltages as they were a lot higher than they really need to be.

Just out of interest Haes, could you find out what revision the chipset is? Mine's an A3 and although I would expect things to be very similar, my board has misbehaved from day 1 and I'm trying to ascertain if the chipset revision might be responsible...