0. Windows. Everything else flows from the monopoly, including Office/Excel.
Remove #3, Xbox is not a big money maker for them, IIRC. Remove #5, Live/Bing are a joke, unless I'm misunderstanding what Live is.
Funny, neither one of us mentioned IE, which was dominant for a long time.
XBox is not a big money maker, but neither was Amazon for a long time. Investors also care about potential.
Bing will probably turn out to be a strategic advantage: If Google creates or dominates new markets, it's going to have competitors who will not want to use its search engine and other online services, case in point: Apple.
I'm sure MSFT has been disappointed with the profits they've seen from Xbox due to the repair charges and higher royalties and sales costs than expected. On the other hand, they earn a ton of revenue from Xbox and have Microsoft products in tens of millions of households.