Diplomacy seems to be the worst defined part of the game atm, I think you get negative diplo from saying that your not going to attack somoene and then going ahead and hitting then hard but there is no real indicator of diplomatic standing that I have seen. I only played a Warlord game and I did station a few units on my border towns but I rolled the AI very easily so didn't get into any complex combat so at that level I would say no, just have a few roving defenders incase.
BTW, how do I check UAC is off on Vista?
Sax.