Microsoft's small investment ($150M) in Apple was really to prop them up just enough to avoid Apple's bankruptcy. Apple may very well have died had they not received that cash injection, and Microsoft, facing pressure from the DoJ regarding their monopoly, could point to this barely-hanging-on company as viable competition.

It is interesting to ponder, in that context, that Apple likely owes its existence to that act.

Apple had over $1 billion in cash at the time of the investment. You can argue that the investment and continued development of Mac Office help shore up investor confidence, but the cash made little difference to Apple's bottom line.

http://apps.shareholder.com/sec/viewerContent.aspx?companyid...

Except it doesn't.

"The unexpected revelation by Apple co-founder Steve Jobs in a keynote speech at MacWorld prompted gasps of disbelief and loud boos from the audience of thousands of Mac users and software developers."

Sounds like they still haven't subsided.

The money seems to be so that MS felt that Apple's success was tied in to it's own, and thus won't skimp on the IE and Office development make them to par with their Windows versions.