Looks like you better be on your toes if you are going to follow in Bill Gates’ footsteps.  From his recent remarks via the Seattle Times about those with aspirations of building a similar sized company today:

"…you’d better see something I don’t see if you want to start a company now."

Or…at least be nimble enough to get out ahead of him.  Microsoft, like Google, has a pile a cash and truck loads of bright people that can attack a market if it suits them.   The key is to complement, enhance, and/or extend product and platform strategies of companies like this.   

Or…if you are clever enough…see something they don’t.