What is the easy way to make the "same" Windows installation of QGIS (same menu, same plugins, same prefs...) on multi-PCs, 10 or 12 laptops?
try create portable QGIS with same plugins, prefs... Some info on site gis-lab.info
How about rolling your own live cd (or dvd or usb stick) with stripped Ubuntu Linux distribution? You can add QGIS, all the geospatial goodies and even your own data. That would leave you with pretty much your own custom version of OSGeo-Live that people can enjoy with or without installation on their machines.
there is a portable qgis for windows here (English!) hope this helps
edit: url http://www.archaeogeek.com/blog/2012/09/12/portable-gis-v3-released/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+ComputingGisAndArchaeologyInTheUk+%28Open+Source+Computing+and+GIS+in+the+UK%29