How to explain 'fortunate' to a 6 year old

At the Grant household we live within our means, which isn't over the top, but we are spoiled.  Scott and I, along with Mat, each have a computer.  Scott has a 360 downstairs, while I have one upstairs.  (Of course this means that the kids each have one as we let them play on it!)  This fact along with vacations, and trips to zoos and museums...the kids have it pretty nice.  We don't go buying them everything they want, nor do we cave to their demands.  

That said, we've had to have several talks of late with Mat about how fortunate he is to have what he does have compared to other children.  We are trying to explain that there are kids who unlike him have never been to Disney (let alone multiple times), do not have a zoo membership, do not get to go once a month or so to COSI, and also, do not get to eat or snack whenever they want.  Some kids, we told him, have to work at his age!  Though no matter what we tell him, it doesn't sink in.  He fusses about wanting more Skylanders, or about having to go to school or do homework or that he wishes he had cooler things, etc, etc.  We realize this is probably due to us having alot of 'wants' in our house instead of 'needs', and that he hears at school how so and so has this or that...So anyway, Scott and I would love to show Mat that yes, we have nice things, and yes, we do lots of fun things.  BUT, we should be very happy about how fortunate we are, and thankful for what we do have.  We should not get upset at not getting something we want, nor should we be fussing over things like doing chores or doing homework (to the extent that he does).  

We're trying to find a nice foundation or charity that would allow Mat to tag along to events to show him these things.  We're also trying to find documentaries, that are decent for a 6 year old to watch that show him these things as well.  

Anyway, that is my long story that can really be shortened up by saying, "It's really difficult to demonstrate or to teach a 6 year old what 'fortunate' really means."