urgent: ibook g4 freezes on apple grey logo

preface:
using microsoft word, saved document and it lagged the computer like no other, for some reason. i decided to reboot by holding the power button, and once I restarted, it loaded to the screen with a light grey background and dark grey apple logo and then decided to not proceed onwards from there.

ive taken the battery out, and put it in about 5 times now, tried to reset the PRAM, it decides not to work when I hold down cmd+s for single user mode upon restart, and it continues to freeze on the logo no matter how many times i reboot.

it seems when a mac doesnt work, it really doesnt work.

Have you tried booting from the system discs?
(Pop in the DVD and hold down 'c' to boot off there)

Have you recently made any hardware changes? Added RAM or airport?

i think your harddrive died. but that's from a university student who has no prior knowledge of full computer hardware but based on experience because my harddrive did something like that when i had a windows laptop. just froze, then had to restart and then froze.