My oldest computers are:
1. A Dell laptop with a P-III 500mHz with 384MB RAM and a 40GB HDD. It is running Lubuntu 12.04 and is used for playing music in the small "comendor" of my wife.
2. A HP Vectra Small Forms Factor with P-III 650mHz also with 384MB and a 250+300GB HDD. It is running XP and it is down in the cabinet and used as file server and it is running "The Dude" using SNMP to monitor my network.
In the cabinet I still have a working 486DX66 with 16MB and 500MB HDD. It runs WfW 3.11 using TCP/IP. Currently I have no space for it.