It's been 20 years since I was allowed by Microsoft to interview Steve Ballmer. (Yeah, I don't know why, either.)

But today, the day Ballmer announced he'd be retiring within a year as Microsoft's CEO , I got my (most likely last) 15 minutes with Ballmer to interview him.

I asked the usual questions that most might. And I asked a couple of the thousands of questions I have saved up over the years, hoping against hope I'd be granted an audience with SteveB.

Here's what we talked about (from our transcript, which I've edited for length):

Q: What was today like for you? After all, you've been one of the most public faces of Microsoft since 1980.

Ballmer: Somebody said congratulations to me this morning, and I've got to say that surprised me, probably shouldn't. When you retire, it's a perfectly reasonable thing. But, of course, my mind's been all around this notion of it never really being perfect time. ...

So I guess it's congratulations. On the other hand, this is my life. I love Microsoft. I love everything about Microsoft. I own a lot of Microsoft stock. I'm going to continue to own a lot of Microsoft stock. But given that my personal plans wouldn't have had me here forever, this seemed like an appropriate time to me to move forward with retirement.

Q: You think this CEO search is going to take a year?

Ballmer: We've (with the board) have all been working together and the board wants to be able to look, and John (Thompson, the lead director on Microsoft's board) can talk about its needs, but a year is a nice long time. And if it winds up being less, but, you know, it just means that we can do things in a very planful and orderly fashion.

Q: When did you actually decide you were going to retire? Was this a sudden decision?

Ballmer: I would say for me, yeah, I've thought about it for a long time, but the timing became more clear to me over the course of the last few months.

You know, we worked hard. We worked hard on our strategy process, our org process. And frankly I had no time to think about it during all of that.... I would say my thinking has intensified really over the last couple, two, two and a half months, something like that.

Q: So when did you finally decide?

Ballmer: Officially, a day or two ago. We had a board call. When was that, two days ago? And it was really two days ago ... I would say that we really -- I finalized and we finalized that this was the right path forward.

Q: Did Chairman Bill Gates ask you to stay or go?

Ballmer: No. Bill -- I mean, no. Bill respects my decision. I mean, it's one of these things when if it's -- you know, ultimately these kinds of things have to be one's own personal decision.

Q: What's next for you now?

Ballmer: Frankly I don't know. I haven't spent a lot of time -- I don't have time to spend actually even thinking about what comes next. I'm not going to have time to do that until the board gets a successor in place.

My whole life has been about my family and about Microsoft. And I do relish the idea that I'll have another chapter, a chapter two, if you will, of my life where I'll get to sort of experience other sides of life, learn more about myself, all of that, but it's not like I leave with a specific plan in mind.

Q: Single biggest thing you are proud you did at Microsoft. You can just pick one:

Ballmer: I'm proud of being I would say a significant part even of the birth of intelligent personal computing, the notion that people use computing technologies, whether that's phones, PCs. I mean, we kind of birthed that over the course of the '80s and the '90s, and that's had such an unbelievable impact on people's lives. I would say a billion plus people and now more with phones, even if they're not all our phones, I'm very proud of what we've accomplished there.

If I had to sort of couple it, I'm very proud that we were able to make this incredible impact on the planet and at the same time do a good job for our shareholders.

Q: Your biggest regret?

Ballmer: Oh, you know, I've actually had a chance to make a lot of mistakes, and probably because, you know, people all want to focus in on period A, period B, but I would say probably the thing I regret most is the, what shall I call it, the loopedy-loo that we did that was sort of Longhorn to Vista. I would say that's probably the thing I regret most. And, you know, there are side effects of that when you tie up a big team to do something that doesn't prove out to be as valuable.

For more, check out Part 2 of my convo with Ballmer (and Thompson) . We talk CEO succession planning, why Microsoft doesn't want to 'just' be an IBM and more.

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