Maybe this

http://icarus.uic.edu/~ssenne1/

will help you..

I have AMD Duron 1100 with 512 sdram and Geforce2MX, on Gentoo box with nvidia drivers up to date and working, with gentoo kernel 2.4.26-r9

i installed on gentoo after updating portage tree :
#emerge planeshift
#emerge crystalspace (no clue if it helps here)

Then :
#cd /opt/planeshift
#/opt/planeshift/pssetup -w
then changed rendered to software like suggested in another thread, and 800x600 and 16 bits.

Then i run the client. It works, but i have incredible lag in game. Well, looks like freezes, like if i had 2 FPS....
I tried the rendered opengl option, it is same (it only changes the textures, but it is 2 fps still !).

And i have no clue what to changed to make it work properly. However, it doesnt crash or anything, it is just this 2FPS thing that make it unplayable !:(

Maybe i will try with 8 bit, however 800x600 16 bit is very low even for a my low end comp.