This is a tutorial used to change GUID's and Group ID's, aimed specifically for careers. I'm including the file (a powerpoint), and the link to the full thread on Mod The Sims. I hope that this will prove useful to any career creators on this site (I notice a lack of them), and I very much hope that it's relevant to any other users having difficulty with GUIDS.
Superfly
http://forums.modthesims2.com/showthread.php?t=85728