I recently had the dubious pleasure of getting Kontact to work on windows, and after two weeks of agony it also yielded some results =)
Not only did I get Kontact to build on windows (sadly still something to be proud off), it is also largely functional. Even timezones are now working in a way that you can collaborate with non-windows users, although that required one or the other patch to kdelibs.
To make the whole excercise as reproducible as possible I collected my complete setup in a git repository . Note that these builds are from the kolab stable branches, and not all the windows specific fixes have made it back upstream yet. That will follow as soon as the waters calm a bit.
If you want to try it yourself you can download an installer here ,
and if you don’t (I won’t judge you for not using windows) you can look at the pretty pictures.