[MEDIA=youtube]ZSlaN5jxAyU[/MEDIA] Thanks to Pit Bitch Bayley for this one!
Sir needs one of these on some shite olde Yam XT http://www.snomox.com/ More easily available than a Kettenkrad.
I saw those (or something similar) at the Dirtbike Show a few years ago. They had a quad kitted out with them too - looked very Mad Max.
To see Mad Max on snow you only needed me, my old Ford Sierra and wait for people to leave the 2100m parking at the ski resort in the evening Audi offers a more serious "drive on snow"course in Solde, Andorra, with modern A4's.
In a similar vein: http://news.bbc.co.uk/1/hi/england/oxfordshire/8458822.stm Checked on the gingeometer.