PowerMac G3/450 with 1GB ram and 2TB external RAID (via eSATA/PCI SATA card) & PowerMac G4/500 with PCI SATA card, 250GB boot drive and 2x 3TB SATA drives.
G3 is my server and has 2x Gigabit NICs, while the G4 is a glorified 'NAS' and has one Gigabit NIC. Both of these Macs are headless. I access them via VNC screen sharing.