Oh, and Windows NT, 2000, XP, Vista, and 7 all have their roots in OS/2
No, they don't. Or rather, the Windows NT project had its roots in the OS/2 project, but Windows NT (including later versions like Windows 2000 and finally Windows 7) did not have their roots in OS/2.
Windows NT (then NT OS/2 or OS/2 3.0) was started by Microsoft to replace OS/2. The original plan involved keeping the "OS/2" name and API (what programs see and use) but the NT OS is very different from OS/2 and was written from scratch.
OS/2 was based on the 80286 CPU and used the 286 memory model. Later versions used the 386 model as well, for 32 bit programs. Windows NT doesn't have any 286 compatibility or legacy.
I can think of only five things that Windows NT got from OS/2:
1. The file system model and the ability to read from and write to OS/2 HPFS file systems (removed in Windows NT 4.0).
2. The OS/2 subsystem that could run 80286 OS/2 code (removed in Windows XP).
3. The command interpreter cmd.exe (extended in Windows XP and above but not in OS/2).
4. The drive letters (which OS/2 got from PC DOS).
5. Some ancient authentication mechanisms that sometimes pop up in database applications.
That's it. Linux has more OS/2 code in it (JFS file system) than Windows NT. (And Mac OS X is based on the same kernel as OS/2 for PowerPC was.)
(The original Windows NT's version number 3.1 can be said to have derived from NT being "OS/2 3.0" at a time. But it most likely came from Windows 3.1 which it resembled and was supposed to replace as well.)
