Impressively, a member of the Windows Club forum that goes by the handle of hackerman1 has gotten Windows 7 to boot on some pretty ancient machines. At the top of the configurations, he installed it on a system packing a 266MHz Pentium II, 128MB of RAM and a 4MB graphics card. After succeeding, he decreased the RAM capacity to 96MB, which also handled 7. His experiment came to a temporary halt after dropping the RAM to 64MB. Hackermans fun wont end there, though. He plans to try and get Windows 7 up and running on a 166MHz Pentium I and 1MB graphics card next.
There is no mention of install or boot times for the Pentium II system, but other forum members have provided the information for a Pentium III PC. They say it took the antique system 17 hours to install Microsofts latest OS, and a patience-shattering 17 minutes to boot