keeping charachter facing in the direction its travelling

Question

ok. i have gotten some answers to this on other boards but its all in c++ and older directX ( Not directX9 & c#, which is all i know).my problem is i have a charachter. at the moment he is in a room. when he hits a wall ( or before) he is going to turn to avoid the colission. the problem is keeping the charachter always facing the direction that he/she is travelling. i am viewing the scene from a fixed position over head. the only things i have to work with is my current position, my last position and the fact that the charachter can not move along the y axis ( i am not giving the ability to jump).can anyone help with this, in as simple a way as possible, using directX 9 ( and hopefully c#)? thanks all