I don't know the nitty-gritty details of what went wrong in the development of Vista, but I can't shake the feeling that they simply waited too long between OS

I don't know the nitty-gritty details of what went wrong in the development of Vista, but I can't shake the feeling that they simply waited too long between OS version releases. I think they could have avoided a lot of trouble had they realised, say, 2-3 years after XP that Vista was in trouble and ported some of the new stuff over to a less ambitious upgrade to XP/2003. The remaining planned changes could then have been done in the following version. Previously, their product cycle was around 2-3 years, except for 2000->XP (1 year), and NT 4.0->2000 (4 years). They took almost 6 years to upgrade their desktop OS with Vista, and made changes almost at every level. People hate change. That includes both end-users and developers of end-user software and hardware drivers. I don't think you can just force large-scale changes to something as fundamental as an OS, you have to spoon-feed it to the users. Breakages in the layers on top of it won't be too catastrophic, are fixed more quickly and thus pissing users off. (I didn't really follow anything Mac-related during the time of the MacOS 9->10 switchover, so I don't know how they got away with that) Note: I primarily use Linux; I only have Windows (XP) installed for playing games and testing, and I'm putting off the Vista upgrade for later. In contrast, I usually upgrade my Linux system shortly after a new version of my distro (OpenSUSE) is out, which is typically every 6-8 months: the changes between versions aren't massive and the inconvenience caused tends to be minor.