Yes, I feel obligated to be nice to people when they aren't nice to me. Should I still act really sweet to them and everything when they are rude to me? I'd like your opinions. Thanks.

To the fearful it is threatening because it means that things may get worse.It has a considerable psychological impact on the human mind.To the hopeful it is encouraging because things may get better. To the confident it is inspiring because the challenge exists to make things better.
If I deal with people that aren't nice to me, I give them just as much attention that they deserve. If it is work, I keep the conversation to work related things, I will say "Hi" when spoken to, but I avoid personal or chatting situations. At play, I ignore the people, and only speak if spoken to.

It really depends on "Who You Want To Be". Others see how you relate to people, what type of person do you want them to see. You have to look at yourself in the mirror each morning. Act in ways that make you proud to see your reflection. Most importantly, follow your heart. If you are overly nice to someone, and allowing yourself to be lessened by that person, your are not doing your self-esteem any favor. I try not to let my upset at others encourage me to lower to their level. By treating them without anger and rudeness, I maintain my integrity. By walking away when I do not want to deal with them, they know that I do not appreciate their behavior.

hope, it will help u,
take care
Richard:)

Excellent answer, Richard. Very helpful advice also for me.:) I really dislike 'getting on the wrong side' of anyone, even if they've done me wrong. Must be the fear in me I guess. Thank you heaps for your thoughts.

I am the same way, most of the time.  I think for me it stems from years and years in the restaurant business where "the customer is always right".  My way of dealing with people who are not nice to me is to "kill them with kindness" -- I really go over board (very obviously so) w/niceness to people who are mean.  What it ends up doing is making them look really stupid, sometimes even making them feel really stupid (but not always), and i can walk away and know that i am still a nice person, i didn't have to insult or offend anyone to prove anything!

Yes, I experienced my share of it, too. These people seem to suffer terribly and so, try to take it out on other people. Things get even worse when they are in leading positions; such as your foreman or boss. (Remember: If you want to really get to know someone, just give him/her power!)
Thus, I regard and treat them as ‘emotionally sick people’, try to avoid/ignore them, but when I have to deal with them I just do the necessary. 
Occasionally, I even surprise them with a little gift; just as one does with ailing people. Little else one can do to change them for the better.

In fact I met people who simply enjoy hurting other people. That's the only way they know to enjoy life, imagine!  How come?  I guess many of us inherited and/or environmentally aquired lots of negative pre-dispositions; such as greed, selfishness, power-hunger, possessiveness, aggression, rage, envy etc. Thus, the only way we ever could rid ourselves of these evils is by systematically dismantling them and aquire postive pre-dispositions, instead. Simple, isn't it? :)  >>> I'm willing to do it and if you are ready for it, then there are already [u]two[/u] of us! Sadly, our society seems to rather promote the former... and our moral preachers and teachers do little/ nothing to reverse this trend.