Be careful with the 160/320+ FSB settings if your CPU can handle them. I don't think that board throttles the PCI clock right unless you lock it down at 166. You'll still be on a 1/4 divider, pushing your IDE drives and PCI cards to 40MHz or higher and they might get pretty flaky. The AGP will get pushed pretty hard also, and can cause some issues too.
The Thoroughbred XP cores are good buys. Most have multipliers unlocked to some degree so you can easily manipulate the FSB/Multiplier configuration to tweak some extra muscle out of them. I have the 1700+ XP (normally 133 X 11=1463) that really boogies at around 1800 by running 156 X 11.5 or even better at 163 X 11.
If it ain't broke don't try to fix it! But, hell if you can tweak that bastard just a little bit more....hehehe.