How do you get your dungeon keeper 2 in to window mode

click start and type "Regedit" into the run box.
Navigate your registry to "Computer\HKEY_CURRENT_USER\Software\Bullfrog Productions Ltd\Dungeon Keeper II\Configuration\Video"

NOTE: You must have run DK2 at least once for this to exist.

double click the registry key "Screen Windowed" set the Base to "Decimal" and change the value data to "1"

Run the game and it will be in window mode (note: this has been known to not work at all or very well on Windows 7 and windows Vista, especially 64bit versions)