Graphical interface can't boot

[Yukimi Daifuku]

Hello everyone. I'm quite a noob with linux but i've already searched 
the web a lot before asking. After having
installed YDL 3.01 on my iBook G4 800/12", it tells me the GUI cannot 
start, i need to enter a root password for it to try with a 'standard' 
config.
I did and still it doesn't work, so i typed in root "Xautoconfig 
--fbdev", hoping it would solve the problem, it created a file 
somewhere but after restarting the machine, still, it fails. my card is 
an ATI radeon mobility 9200 32Mb.
Before installing, I took care to format my HD in 1 partition in "free 
space" mode, like i was told to do by many websites.

Thanks a lot for your help everyone

Fabien Besnard