When I moved my box from suse to slack I copied over
the old /etc/groups, /etc/passwd, and /etc/shadow entries
for the users into the new files. It's pretty easy for the
most part, you just have to make sure UIDs/GIDs don't get
shared.
Scott
-- ossuary.net --
"Time provides the rope, but love will tie the slipknot, and
I will be the chair you kick away." -Magnetic Fields