Using the spacebar to boot the PC

Originally, my NT machine used to powerup when hitting the spacebar (this is on an HP Vectra VL8). It no longer does this, and I’m not sure of what I did to make this go away.

But I would like to know how to get this working again, since I am performing a MAC to NT migration and all the MAC users are used to turning on/off their systems with the handy keyboard button.

Thanks