http://www.tuaw.com/2007/09/24/leopard-to-exclude-800mhz-systems/
Looks like Leopard will require an Intel processor, PowerPC G4 (867 MHz or faster), or G5 processor. There are a number of places that will upgrade your older machine, so there may be hope for you "vintage" users yet!
http://daystartechnology.com/
http://www.powerlogix.com/products/index.html
http://www.sonnettech.com/product/processorupgradecards/index.html
etc.
Looks like Leopard will require an Intel processor, PowerPC G4 (867 MHz or faster), or G5 processor. There are a number of places that will upgrade your older machine, so there may be hope for you "vintage" users yet!
http://daystartechnology.com/
http://www.powerlogix.com/products/index.html
http://www.sonnettech.com/product/processorupgradecards/index.html
etc.