Multiple Library Questions...(Help Needed)

Okay, I did a search but couldn't find the answer I'm looking for, so I need help. I own a 60GB iPod Video, I have over 5000 songs in my iTunes library. I don't want to shuffle my whole music library, so I got a 1GB Nano. I know the 2 methods you can use when you have multiple iPods, but I don't know if they're appropiate for me.

My goal is to be able to use the "shuffle" feature throughout my Nano's entire music library. I expect to change the songs on my Nano at least once a week. If I go the multiple user account route, will I have access to my 5000+ song iTunes library? My concern with the other method is that the songs that will be on my Nano will be trapped in a playlist, and unable to be shuffled. Is there a way I can do this?