The initial install of Windows 7 beta went pretty quickly, and the whole thing was without incident. There was very little for me to input beyond the type of install I wanted. Having done more than my fair share of installs with previous versions of Windows, I expected it to take a lot longer. Windows 7 first impressed me by identifying my TV and configuring it as a secondary display device before it had even finished installing itself. Every previous version of Windows I've used has had to be told there was another monitor attached, and this one picked up a TV. I like that quite a bit; it reminds me a bit of BeOS, an alternative operating system I used to use years ago.
All in all, I would say the install took maybe half an hour. Possibly up to 40 minutes, but no more than that. That, of course, is before you get to all the post-install work that needs to be done on a clean computer - installing apps, setting it up the way you want it, etc. I'll begin to get into that in part 3.