steve ballmer1Last week, Microsoft’s CEO Steve Ballmer announced that he’s going to retire within a year, as soon as the company’s board picks a successor.

He later had a chat with ZDnet’s Mary Jo Foley about his tenure at Microsoft and what’s next for the company.

During the chat, Ballmer said his biggest regret after all his years Microsoft was Windows Vista, a version of Windows that launched in 2007 to horrible reviews and customer headaches. Microsoft had to rework a lot of the kinks in Vista with Windows 7. It was a disaster.

Here’s what Ballmer told Foley about Vista:

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.

Credit: Business Insider