Having already switched all the accounts on my dual-boot system to use
the "Windows Classic" theme. I decided I'd try to get rid of the
abdomination of the XP theme from the login box. For those who need to
remove it, you need to go to Control Panel->Administrative
Tools->Services. Then double click or use the context menu to get to the
Themes services properties. Change its 'Startup type' to 'Disabled'. You
may need to reboot. Now, no more damn themes.