This it what I use nightly from a job in SS 2000 to create a script file that will rebuild the logins.

osql -E -Sservername -Q"sp_help_revlogin" -o\\Sharename\DirName\rebuild_logins.sql -w512

Like a previous poster mentioned, there is a version of sp_help_revlogin for 2005 and osql (from what I've heard) is no longer used in 2008 either.

Oh well, if you haven't figured it out yet, this might point you in a direction.

Steve