Microsoft is offer free Vista to Windows 7 upgrade to participants of  Windows Media Center TV Ambassador program. The prizes also include free: software, games, Xbox 360, ultimate home entertainment system, and laptops. Microsoft is accepting participation requests only from UK residents “Become one of our TV Ambassadors! If you’ve already got Windows Vista Home Premium or Windows Vista Ultimate, you could receive a free TV tuner valued at £60 so you can enjoy watching and recording live Freeview TV channels on your PC,” revealed. “Just turn it on, watch and record your favourite TV shows from over 50 Freeview channels including BBC Three, ITV2, Film4, E4 and Dave, and tell us what you think.”

More info: Singup | Windows Media Center Windows Help