Hmm... well.

• I have a drive that holds just Max & Poser. I know Poser needs lots of room to grow so there it is.
• I backup the entire poser directory to my fileserver every few days.
• All my work goes in a separate drive organized by client and project (I consider myself a client so I can track how much time I spend just messing around).
• All downloaded files are put in a separate directory, in either a "free" or "registered" folder in a subfolder marked "unchecked".
• Those files are unpacked and the licenses checked. They are divided into things that are "OK for commercial work" and "OK for personal work".
• ONLY things that are OK for commercial work go into my Poser structure. I don't want to make a mistake and I have no interest in trying to keep track.
• The stuff that is only for non commercial use is archived but never installed.

There ya go!