Battery life of my ASUS EEPC 1000HE running Fedora 11 KDE with locally built eee-control: 5-6 hours
Battery life of my ASUS EEEPC 1000HE running factory WinXP: 3-4 hours.
That's with wifi, and maximum screen brightness (with eee-control's SHE set to powersave)
What do you have running on the machine? I can't imagine that Fedora would cause that much of a drain unless you were doing something mad, like running apache off of it, or if there was something missing in your kernel. That simply does not make sense.