It may be one of life's imponderables... Apple is still releasing security updates to OSX 10.1 four years later... Earlier versions of the OS did not have automatic notification.
So, the short answer is: No, I don't know. ;^)>
Oh, what the heck. One of the reasons I got the Mac is because I have already spent more time upgrading computers than I like (it's fun for awhile, but then it gets old - sort of like mowing the lawn).
If this computer lasts 4 years without me having to do an "upgrade", I will be certainly happy.