Well, there are a few views around as to how it got to "7". This is mine!
1. 3.1
2. 3.5, 3.51 (minor update)
3. 4.0
4. 5.0 (2000)
5. 5.1 (XP)/5.2 (Server 03) <- group them together, one client, one server version, just numbered differently
6. 6.0 (Vista)
7. 7.0 (7)
Hey take it easy on us old uns, Celestra. I was a "1" user. But before that, I don't know why they were left out of the numbering system, there was Windows version1, and two versions of Windows 2. There was also a 2.1 computer specific release, for the 286 and 386.Then quickly came Windows 3.0, a bit of a "millenium" release. I used them all and up until 3.1 was seriously considering changing to a Mac.