Windows 7: How Slow Can You Go?
PCWorld has a story about a user who is testing the limits of the system requirements for a bootable, working installation of Windows 7. He just got it working on a Pentium II 266 with 96MB of RAM and a 4MB video card. Funky.
He continued to alter the memory amount, achieving success with two of three setups: 128 MB and 96 MB. Unfortunately, Windows 7 didn't seem to enjoy only having 64 megabytes of memory to work with, marking hackerman's stopping point with that version of the experiment.