I know first-hand how stubborn it can be to get someone to convert, however, it is slowly happening. I work for a multi-national company, which (my portion of the company, the lab) is 2/3 European. Engineers spend a lot of time just converting numbers back and forth just to figure out what test results mean.
So, in building a new lab, my software group is going to create all the interface screens entirely in metric. Since the data analysis tool can display the information in metric or english units on the fly, the people that don't want to change won't have to, but we'll force the test techs and the majority of the engineers to the metric system (and the software team as well, I suppose).