http://www.linuxprinting.org/ has information and how-tos:
http://www.linuxprinting.org/show_pr...amsung-CLP-500
There don't seem to be native
CUPS (the most common printing system for GNU/Linux, also used by
Ubuntu) drivers for either of your printers; the
Lexmark isn't even documented. Bad news, overall. A tip: If you can get your hands on a
HP printer, you'll be fine. Thanks to
HP's sensible policy on drivers, those machines simply work.
Anyway, you should update your
Ubuntu installation - your laptop can easily run
Ubuntu 8.04; you get a version that's actively maintained and supported that way - and thus, a better chance for a solution. However, given the fact that working models exist, the incentive for developers may not be very high to fill the gap.
M.