lshw

lshw (Hardware Lister) is a small tool to provide detailed information on the hardware 
configuration of the machine. It can report exact memory configuration, firmware version, 
mainboard configuration, CPU version and speed, cache configuration, bus speed, etc. 
on DMI-capable x86 or EFI (IA-64) systems and on some PowerPC machines (PowerMac G4 is known to work).