The issues you need to know are...
1 Temps... keep the full load temp below 55f
2. With re; to #1 you will need to increase the vcore (CPU voltage)
3. As you increase the CPUs FSB the PCI and AGP will also increase.
When you increase the CPUs FSB (Front Side Bus) from 166MHz you have to watch the PCI and AGP bus speed... do not let the default 33MHz PIC get above 37MHz.
4. That board is made in 2 revisions ie . Rev1 and Rev 2
The Rev 2 is a little more OC friendly with the 400a chip set.
5. You may find advanced OCing optiond with CTRL F1 .. not sure on that BIOS.
Dang did I have a bunch of typos to fix