I know this one... wow! from a girl...
Well it depends on where you live....
You can get away with letting it sit for a year in the southern states... but if you live anywhere where these cold, you wouldn't want to do that -- it will cease.
There is additive that you can put in your engine -- than you can pick up at pretty much any auto parts store. This will prevent the engine from ceasing.
But the best bet is if you're leaving the car anywhere where there's going to be people around it (aka watching it, etc) to have them start up the car and let it run for 10 minutes - at least once a month -- and a couple times a month if you live in a colder area.
Check out your area auto parts store, and they can help you out -- usually there is at least one person there that knows what they're talking about... lol (some of the people that work there are dim wits and don't know what they're talking about half the time).
If you need any further help trying to find the right additive for the engine, let me know, and I'll look up the exact names of some stuff (I don't know if off hand).
Hope I could help!
(I know cars pretty well -- my husband is into cars and we've had our share of fixing them up... )