Running leopard can be done without an actual 867Mhz CPU, and the extra 200-400Mhz from that motherboard wouldn't make it much faster. If you want to trick the installer into thinking it is a faster computer, [http://www.lowendmac.com/osx/leopard/openfirmware.html|here] is a good guide (Note, you will need at least 512MB of RAM, or you can expect a really, REALLY slow computer.)