They've been running the replica of the first stored program computer in Manchester today to mark the 60th anniversary of the original. This was the first modern computer. There had been digital computers before (Colossus and ENIAC), but they weren't general-purpose machines and had to be re-wired to get another program into them. In contrast, the Small Scale Experimental Machine had its programs loaded into memory. You want it to do something else, you load another program. 'Nuff said. It changed everything, but I think it might be in line for a radical case mod, judging by the picture I took of it on Monday:

EDIT: Or maybe this IS the case mod...