the non-pae is probably better for xubuntu and lubuntu
Phoronix: Ubuntu TB Decides On Future Of Non-PAE Kernel
The Ubuntu Technical Board met yesterday and they decided on the future of non-PAE Linux kernels within Ubuntu, a decision that affects 32-bit users on older hardware...
http://www.phoronix.com/vr.php?view=MTAyNzM
the non-pae is probably better for xubuntu and lubuntu
My IBM T42, that sees extreme daily use, has a 2.1Ghz Pentium-M with 2GB of ram. It runs a non-PAE kernel. I think i've booted a PAE kernel, and didn't notice anything bad happening, so this may be moot to a certain point?