Well knowing windows does not help in this matter :P Just kidding. Once you get in the graphical mode press CTRL+ALT+F1 (you can press F2 or F3 or F4 for the same effect) to get to console mode. Don't be affraid of the command line. You said you use Fedora 3, so here is a brief explanation on how to comment out the dri part.
once you are in console mode (text mode) login using root as username and type in the root password.
To prevent REINSTALL copy the xorg.conf file first. type in the command:
cp /etc/X11/xorg.conf /etc/X11/xorg.conf.old
(in case you mess the original, you have a backup, which you can copy back, with the file names changed .old to original)
then run emacs (it's an editor) like this:
it will open the xorg.conf file in the EMACS editor.
You will probably need to get accustomed to emacs, but here is a brief usage of the editor and a brief explanation of config files (ending with .conf ussualy).
lines that start with # are commented out, sou don't bother commenting those, as they are already commented out.
to initiate a search in emacs, press CTRL+S (if you press anything else, just press ESC a couple of times to abandon any commands you might have started. The commands you initiate are printed in the bottom line of the screen. The word search should be printed in the bottom line of the editor. then just type in dri and it will find dri words in the file and highlight them. Just scroll down through the file to see the highlighted words and where they appear. I don't really know how to solve your problem, but it can't hurt to try things. Find the dri line and comment it out. You comment out a line by putting a # as the first character in that line. Any text from the # character on is considered a comment. You can place a # anywhere in the line and you comment the rest of the line out.
once you are done (the dri part commented out)
save the file, this is tricky to non linux users.
press CTRL+X, CTRL+S (this means you press CTRL+X and then press CTRL+S to save).
Again if you misstype, press ESC a couple of times to clear the line at the bottom of the editor.
ok, now all you have to do is restart the X server. press CTRL+ALT+F7 to get back to graphical mode.
Once in graphical mode, press CTRL+ALT+BACKSPACE (this will restart the X server, usefull if the X server lock up for any reason at any time, sure beats the reboot, which is usually not necesary.)
Hope your X works this time