I'll add a data point too.
My old laptop used to run GNOME, Mozilla and a plethora of development tools very well. It has 192MB RAM, and I used it from 1999 to 2006.
I don't expect a modern GUI to fit, but I thought at least a text console with a current distro would be useful as a VPN hub, remote serial ports etc. for I have quite a large network of embedded systems which I develop on remotely.
I quite like Ubuntu Server, so I tried installing Ubuntu 11.04 on my old laptop with 192MB RAM, and it couldn't even run the text-mode installer. After an hour of swapping I gave up. Debian was not much better.
In the end I used debootstrap on another machine to make a Debian image, then copied the filesystem over. It runs fine, but the basic installer doesn't fit -- on a system that used to run GNOME and Mozilla very well.