A vanilla install of Windows XP uses 1.2GB of disk space.
But 83 critical security patches need to be downloaded
and installed right away. These add 5.3GB to the system.
That's 4 times as big as all of Windows XP!
(This is all according to a recent RISKS article.)
I'm reminded of the story of how a statically-linked
"Hello, World" program was over a megabyte. It turned out
that all the Unicode characters were thrown into libc.
I'm thinking that there has got to be a similarly interesting
reason as to how security patches can be massively bigger than
the OS itself.