Update, 2010-06-19: I use a different approach than the one described in this post since I upgraded to Ubuntu 10.04.
I successfully extended my Kubuntu desktop to a second monitor. I’m running Kubuntu 8.04 (updated on 2009-07-03 for 9.04) on a ZaReason BigLap, with an Intel video card and a Dell external monitor (connected via VGA cable – the BigLap doesn’t have a DVI interface).
antsy and uncle ham 