Gateway PC
This was my second 'IBM-compatible' PC after the little Shuttle system. I bought it from Comet in Shed City in 2005, shortly before they packed their tents and set off for Millbrook. It has an early dual-core processor — the Pentium D — and has been switched back and forth several times between Windows XP and Ubuntu, both dual-boot and "pure". It's currently a spare Windows XP system which has from time to time proved invaluable when other systems have been, shall we say, sickly for whatever reason.
Now that I've equipped myself with a laptop PC running Windows 7 Pro I have finally 'retired' the Gateway. It's sitting, disconnected, in Junior's room.
Updates: the laptop PC ran Windows 8 Pro for a while, but is now [March 2015] a Linux Mint 17.1 system, the Gateway is now due to be turned into a FreeNAS system for Junior, and Comet is now defunct. Is this progress?