And there i was thinking i was a geek!

I had a look at that windowsecurity.com article and i must admit, a lot went over my head. So in simple laymans terms this is my understanding of it...

Program X, takes file Y and runs whatever standard process against it. File Y, while appearing to be a certain length, is actually longer by whatever means and therefore overflows the allocated memory space into space reserved for program X? The excess data outside the allocated space is then immediately evaluated (by windows presumably rather than program X) and if found to be a properly formed executable automatically run with the priviledges of the original program X?

Again i stress my understanding of the machanics of it all are very limited and i have a load of questions that i'll save for now but is that the general gist of it?