run firefox?
yes, you should be able to find the entry in the registry but your better off using a legit program to prevent damage to your reg. Also some of those Hijacks are sneaky and hide themselves in there. So altering one thing in the reg won't fix it.
Reg Key for your homepage: (XP/iex6.0SP2)
HKEY_USERS\software\micorsoft\internet explorer\main\start page