As said in the title, install ubuntu and let them use a dedicated virtual machine with windows XP.
Make a snapshot after the initial installation and always revert to this snapshot.

Of course, there are other virtualization solutions, so you may have your preferences, but VMWare may still have some advantages over others (dual screens, sync USB, ...)

For a dedicated solution, you can buy a Falcom Mambo (http://www.falcom.de/products/personal-tracker/mambo/)

Dedicated GPS tracker with an emergency button
Long battery life
Very Open

as the parlament changed the law to introduce biometric passports, a group of citizens sucessfully launched a referendum.
As a result, they're going to vote on this in May, so this will be a good indicator as the people will directy decided.

And before other people jump on the democracy aspect and representation in the EU, don't forget that many EU government/parlament (including mine) already introducted biometric passports and are directly elected.

It will be also difficult to guess what the swiss result will be as they already 'confirmed' different EU decision in such referendums.