is the 'keyboard' on the presario notebook a one-piece deal like, say, the apple i-book? some laptops are, but if it isn't, you should be able to get a screwdriver underneath it should have the button contact int he middle, two or so posts to keep the spacebar horizontal, and a spring somewhere....basically like a compressed version of a normal keyboard.
but if you have the one-piece dealy things....i have no clue.
-sandlizard