Re: Gates quote
I personally don't see Ballmer as a right person to be at the front of the Microsoft (mainly because of his physical appearance not expertise).
Nevertheless good thing or products while he is CEO are:
Win7, Office 2003,2007,2010, Win Server 2003, 2008R2, Exchange Server 2003, 2007, 2010. SQL Servers ... (You have mention some of this already).
Windows 8 is fantastic product and it is excellent way of moving on from platform that we all know so well.
Surface project is fantastic.
Windows Phone 7.5 and WP8.
WP8 in particular is great mobile OS.
On the question what went wrong or if you like what was mistake I believe Bill Gates was referring to Windows mobile 6. That indeed was mistake, no doubt about it. Windows Vista yes that was mistake. Zune - personally I don't need anyone to make me my collection of mp3 music or similar. Once I have paid for my CDs I know how to compress them and put then on my mobile device. I don't want to pay it again (most of the iPod users, as well, will share the same opinion). But lets say Zune was also not very good product or if you prefer mistake.
There is also other great products from Microsoft like Visual Studio, Azure, Windows 2012 is still in early days but already has some brilliant reviews form experts.