Newbie help with X Server on ibook G3

[James Dunn <james@4thharmonic.com>]

I am trying to get Debian up and running on my iBook G3, 900Mhz, 640MB RAM. I ran dpkg-reconfigure xserverxfree86 and then edited the /etc/X11/XF86Config-4 file with nano as it was still not working. I amended the file according to this: http://www.cattlegrid.net/~christophe/titanium/XF86Config-4

Still no luck. There was an error in this Section:

Section "Monitor"
	Identifier   "LCD"
	Option       "DPMS"
	HorizSync    40 - 100
	VertRefresh  40 - 120

So I deleted these lines, typed startx, and it was working, but with fuzzy lines. I assume this is to do with the Sync or refresh rates?
Now, when I boot up, I just get the X Window System login screen, but I can't seem to login. I've tried with root and my user name.
Please help! How can I disable the X Window System / X server to reconfigure it again from the command line?

Many thanks

James