I used my system as a normal user. I don't think it became much more secure, because the method was to set everything setuid that said it hasn't got permission to something.
It was, however more convenient with ssh and it wasn't so terrible to see that I use a Linux as root everytime. If I wanted to see that, I wouldn't buy a Zaurus...
Ping works only as root, but it's a busybox feature and I didn't bother myself with it.
I can't say specific things, because now I have a-not-workink-dev-version-of-the-ROM on my Zaurus. (Laze, pleeeease release the RC ROM! )
So, I think to use X with a normal user, try to find the X executable (which is somewhere in the /etc/X11/ or somewhere in the /usr/) and make it setuid. (# chmod +s /dir/filename -- or use mc )
Zumi