A stray comment today about Windows not working on ARM machines, by someone who thought all OLPC laptops had moved away from Linux, reminded me to reaffirm something:
Every XO we have ever made shipped from the factory with Linux. The 2M+ XOs running Linux is one of the largest deployments of Linux in the classroom anywhere in the world, and the largest in primary schools.
A few thousand dual-booted into Windows [XP] as well, either at the time they shipped or after being reflashed – after a Microsoft team modded a version of XP for the XO, and our firmware made dual-booting possible. That was an impressive bit of coding and optimization, and Uruguay in particular was interested in dual-boot machines, testing them in classrooms on XO-1′s, but decided not to continue those tests. The only other machines that ever made use of the dual build were part of programs sponsored by Microsoft. In all, under 7,000 XOs have ever run Windows natively, 5,000 in Uruguay. That is less than 0.3% of all laptops we have ever produced. (In contrast, running software under emulation through wine or SugaredWine is popular in Latin America.)
I have heard of a few teachers that had those machines in at least one class, in Uruguay or Peru, but have never seen first-hand reports from anyone using them. If you visit or know of a school that tried this please share your stories; I would be interested to hear about the experience.