I doubt we'll see an SIS based PCI-E board prior to an intel one - but maybe at the same time.
In that Asus model number, P4 indicates it's a P4 board, S indicates it uses an SIS chipset, and 800 indicates the maximum FSB speed.
So no, you cannot use an AMD processor in that board. You should be able to use that DDR1 memory as it uses the 665 northbridge.
*Dual PIII-800 @900 i440BX and Tualeron 1.2 @1.7 i815*
In that Asus model number, P4 indicates it's a P4 board, S indicates it uses an SIS chipset, and 800 indicates the maximum FSB speed.
So no, you cannot use an AMD processor in that board. You should be able to use that DDR1 memory as it uses the 665 northbridge.
*Dual PIII-800 @900 i440BX and Tualeron 1.2 @1.7 i815*