Have you considered the Kingwin KT-424 case, it is similar to the Coolermaster, and it it excellent quality. http://www.kingwin.com/pdut_detail.asp?LineID=&CateID=1&ID=153
I have built quite a few business systems with this board and I don't remeber anything in the BIOS to allow for setting the FSB to 166. Since it is a 133 board, hence the name A7N266, I think it would be best to run a non Barton chip.
I have an older Epox 8k5a+ board running an XP 2600+ Barton with no problems. I'm not sure what BIOS I am running, but I did have to flash it to get the board to id the processor correctly. It will not id past a 2800+ when overclocked.