Windows 7. I have an ATT Air Card, recently had an issue that was politely resolved, they give good customer service. Anyway, during the course of conversation it was said that Windows 8 will not work with their Air Cards but they were working on the software and the problem would soon be resolved.
Not networking with ATT to assure the two products are compatible, how stupid is that? Incredible. Windows 7 is OK, I'd sooner have XP Pro. I'm ready for a Mac. Maybe with this failure someone new will step into the gap.