If your used to turning DEP off completely on Windows XP you’ll have a hard time doing it on Vista.
The BOOT.INI file that is in Windows XP is now gone in Vista so you can’t just edit it to turn off DEP.
Windows Vista now comes with a command line tool called BCDEDIT.EXE that will edit the boot configs for you. It’s actually easier then editing the BOOT.INI file but only if you know the command to do it.
So here’s the command, make sure you run in with elevated priviledges.
Turn OFF DEP:
bcdedit.exe /set {current} nx AlwaysOff
Turn ON DEP:
bcdedit.exe /set {current} nx AlwaysOn