GRUB is a boot loader
, that is a software that is written on the harddrive
- usually on the master boot record of the harddrive(MBR).- so it is not supposed to replace a BIOS
, which is a firmware embedded in a writeable chip
A free replacement of the proprietary BIOSes is in active developpment OpenBIOS
, and I will use it as soon it is mature enough.