17" iMac G4 - how do I configure screen?

[yellowdog-newbie@lists.terrasoftsolutions.com]

Hi,

I have an iMac G4 800MHz with a 17" LCD screen. I have twice installed YDL 3.0,
and once Mandrake 9.1, but never gotten the monitor to work in any sort of GUI.
In YDL 3.0, during installation, I can actually select the iMac LCD 17" monitor
(and of course I did), but it still doesn't work when I try to start the GUI.
Either it gives an error and says the screen failed or something, or it starts
and the screen shows a bunch of intricate, colorful, patterned graphical
garbage, somewhat like those "hidden image" optical illusion posters. I've even
gotten to the point, when this garbage is displayed, of logging in and being
startled by the rock-beat music jingle that presumably greets you when you've
logged on. So YDL thought it was working, but my screen was still unintelligible.

For video card, during installation, it defaults to one of the GeForces, with
16MB RAM. My first install, I went with that; my second install, I chose 64MB
RAM (which is what I have).

I also tried editing the /etc/X11/XF86Config file, as recommended on the YDL
website, by adding in the "Monitor" section:

Option "CrtcNumber" "0"
Modeline "1440x900" 129.73 1440 1480 1616 1848 900 903 906 936 -HSync -VSync

I tried it with those lines, and then again with those lines but removing the
existing entries for HSync or VRefresh or whatever they were. After each change,
I logged out of root and back into root, and then tried "startx" again, but
invariably it either gave me the error and returned me to the shell, or it
started the GUI as if it were working when all I saw was screen garbage that
changed subtly when I typed or moved the mouse.

At this point, I don't know what to do - please advise. The Mandrake Linux
installation was even less successful, plus it screwed over my partitions so
that my Mac partitions have apparently vanished (at least from the sight of the
YDL 3.0 installer). Everything was backed up, but I'd like to get this fixed
ASAP so I have a usable computer again, whether it's Linux (my preference) or
Mac OS X (back to the drawing board). I'm writing this from my PC which I
thought I'd never need to lay my hands on again.

If the specific error messages would be helpful, let me know and I'll post them.

Thanks a lot,
Marc Macauley