If like me you only use the home button to wake the screen, and don't want the power button waking the screen whilst in your pocket or when you try to adjust the volume. This is for you.
You need to be rooted and need a file manager that supports root (Root Explorer or Root Browser (LITE version works fine)).
On your phone navigate to system/usr/keylayout
open sec_key.kl in text editor (you can make a backup if you want by adding .bak to the end of the file name and saving - Root Explorer will do this automatically)
delete WAKE from either HOME or POWER (not both!)
save and reboot.