The curious interaction between PAE and NX
Carmen Crincoli
covered
the interaction between PAE and NX on his own blog,
so I'll merely incorporate his remarks by reference.
(And notice again the concession to backwards compatibility.
Without the backwards compatibility work, XP SP2 would have shipped
with NX support and an asterisk,
"* and those of you who have device drivers that are
not PAE-ready will not be able to take advantage of these new security
enhancements. We could've done something to make your systems
secure, but we decided not to do it in order to teach you a lesson.")