I use 7StickyNotes which sits in the systray and spawns a window for adding your notes.
While it offers monitor # and placement configuration that works well, I find that the note (which I don't close) is on the primary monitor rather than the second (where it should be) when I log in.
THis may be a bug in 7Sticky or a Windows issue but I'm wondering if such popup windows can be controlled in the same way as trigger event windows can.