Re: What would be a good flavor for an older laptop?
The most important thing is RAM. You've got plenty of it. The CPU isn't critical when it comes to simply driving the UI. Doesn't matter if the P4 is single core and 32bit and generally a very crappy architecture. Look for a distro based on XFCE or LXDE (you could also stick with Ubuntu, remove Gnome and install something else). Your machine is more than good enough to run them. I'm running Arch with LXDE on a P4 laptop with 256MB of RAM.
PS. This thread is quite a bit off-topic for the Nvidia forum. Perhaps moderators should move it into the General Linux section.