Bit of a newbie here myself Cuzzer - but I think the plot is that you check this page
http://www.v-flyer.com/chance.asp and then you can see what the plane will be - in al probability it is going to be a 747 - 400 with the Nova entertainment system.
There are those cleverer than me who can tell you EXACTLY which plane will be used by using the reservations tool - but I havent got that sussed out yet.
One other tip - have you gone to the VS website and booked your seats yet - this will usually give you the best clues as to the plan being used as they will already have loaded in the flight management detail to let you book your seats - its weird - but it really gets you in travel mode when you have your seat numbers all planned!!!
Have fun in Vegas!!! ( and pack plenty of shirts in case you lose yours off your back!!!)