Just bought this instore, seems a pretty good deal!
The offer isn't advertised on the website but it is online and in store, just checked. If you add the 60 gig xbox to your basket and add the "Sega Superstars Tennis, Banjoo Kazooie, Viva Pinata" bundle to your basket too the price comes to £183.36!! Three games for £19.99 doesn't seem bad to me! :)
link for the game bundle http://www.argos.co.uk/static/Product/partNumber/5668746.htm