We upgraded from Intralink 3.x to Windchill PDMLink 10.2 last summer (M010). I've not done an update yet and want to go from M010 to M020 - do I just install the updated components on top of the existing modules or do I uninstall/install?
Yes, basically it's just an in place upgrade right on top of what you already have. Just don't forget to run the update tool when you're done. (See page 48 of the Update Existing Installation document.)