The funny thing about that, is that microsoft did write the first versions of OS/2 for IBM. Go figure...

Well, they helped, and thats why IBM ran off with file system code that didn't need defragging when they split their relationship, while MS had to write NTFS for NT 3.1

All Windows was originally meant to do was get consumers use to a mouse until they could push OS/2 out the door, since it was delayed by quite a bit. But somewhere along the line IBM and Microsoft got angry at each other and took what they had of the OS/2 code and released something with it. For IBM, OS/2 Warp 3, and MS started NT.