HOWTO/Switch Off the Data Execution Prevention Feature in Windows XP

Courtesy of Filipe Toscano, in case you're one of those people severely hit by the overhead of the new DEP feature in XP SP2 (which is not yet implemented in old Intel CPU hardware), you can turn it off completely by modifying the /NoExecute option in boot.ini:

[operating systems]
%device%\WINDOWS="Microsoft Windows XP Professional" /fastdetect /noguiboot
/NoExecute=AlwaysOff
%device%\WINDOWS="Microsoft Windows XP Professional (no DEP)" /fastdetect
/NoExecute=OptIn

Of course, the usual disclaimer applies - this was built into SP2 for a reason, so you're not actually supposed to mess with it, and if your machine becomes infested with zombie spambots, you're completely on your own.