How about giving kill messages for landing of 1 kill for the newbies / squeakers / 2-weekers. This game has a high enough learning curve that newbies deserve a little recognition upon landing their first kill, it is simple to do, and it can't do anything but help new player retention. It also helps people know who the newbies are so that they can offer counsel and sage advice as it were (like DON'T press Alt-F4 to engage turbocharger, etc.) Once a player has 5 kills, or his 2-Weeks are up, you can always go back to making 2-kills the cutoff for system messages if you want.