That looks like three too many to me.
I don't see why as an Android site we'd care about the difference between WinXP and the rest of the desktop Windows family in a way that needs separate tags (we do have a Windows-Mobile tag as well, but as a mobile device OS that is a a special case, so I've left it out), similarly I don't see why we'd care about differences between Ubuntu and Linux in general. As for "Mac" and "OSX" they're essentially synonyms in common usage, I'd propose combining them into a "Mac-OSX" tag to make it easier to find.
Update have proposed some of these as synonyms (ubuntu as a synonym for linux and windows-xp as a synonym for windows), vote here: https://android.stackexchange.com/tags/synonyms?filter=suggested&tab=newest
I'd suggest that "mac" and "osx" need merging and renaming to "mac-osx" but I don't have the necessary mod powers for that, could someone else help here, please.