If I plug my ipod to another computer's itunes, my musics will be deleted? I'm thinking about use Ubuntu's Rythmbox to synchronize music, but I need the iTunes from my windows to get some apps.

If I plug my ipod to a windows with no musics on it (to get my apps), my musics will be deleted from ipod?
In my experience, it asks you. You can say no. However, I'm not sure if this requires Manually Manage Music to be checked in the Summary tab.

As always, make a good backup just in case.