Intel Pentium 233 mmx with heatsink/fan, motherboard (No dallas battery) some ram and must have some cache ram on motherboard, PCI or AGP but must be small with ISA slots.
Bios should be able to detect LBA HDD.
optional extras depending on price and postage
midi tower case at or atx to match motherboard with PSU if AT.
motherboard with onboard network / USB / PS2 but older din keyboard is fine as long as the serial cables are present.