I can't find a single product on this list that I could say, "yep, that was worth it".
DCOM - a pile of complexity even most Microsoft employees couldn't understand. Different threading models, security problems, you name it. In my early days as Microsoft employee one unfortunate guy decided to implement an app to manage installing latest build of a (different) product and running tests on a couple hundred machines; he spent month fighting DCOM problems.
ActiveX - huge security nightmare in the browsers.
IE3 - don't know, don't remember much.
WMC - windows-based media centers are a failure. Large, noisy, boxes, poor power management, lack of support for MKV in the latest version. Had they done it right there would never be a Roku, and Apple TV would be too late to market. It's failure.
Home server - they should have solved two simple problems: 1) every windows user should have a backup solution according to his budget (starting from $50 and up) 2) every windows user should have a one-click file-sharing solution according to his budget (starting at zero dollars). They failed at both. I guesstimate 90% of windows users still do not have a backup solution. This reflects poorly on the entire platform reputation. So they came up with a $400 noisy, blinking box that needs its own space. These "features" are most often incompatible with female spousal units. Geeks love those gadgets, which is the market they conquered, leaving normal people behind.
WP7 - they jury is still out on that one.
Overall this looks like a bunch of products only a geek could love. Yes, they are cool, but they failed to live up to the Microsoft's then-ambitions - to change normal people's lives for the better.