Great interview, interesting to hear why Charles actually started in the technology industry.
About why Microsoft and technology is so cool I absolutely agree with Will on the Impact 'you' as a developer or whatever can have on someone else's day-to-day activities is really cool, and also the integration part. While I think there are actually two sides to that. First of all the integration we as developers have with the .NET framework and de CLI and CLR to be able to program in whatever language we feel most comfortable with. Also the integration with several technologies like say active directory is actually a great example of this. You can use AD for almost if not everything which has to deal with users and/or authentication.
So great stuff you guys, keep it up 