Something I forgot (I somehow neglected the Ubuntu part):
With newer Ubuntus, you should go and get all (dynamic) Linux packages
matching your architecture, unpack them temporarily, and run "ldd" over
selected binaries, or run "condor_version" to find whether your glibc
is supported (Debian Etch and RHEL5 don't match, for example). Then
choose the most "recent" "officially supported" distro that has standard
universe support.
My guess: RHEL5/CentOS5 should be close.
And, of course, please report so we can remember in the future :)
Steffen