Might want to check out the A* path finding algorithm, lots of info at:
http://www-cs-students.stanford.edu/~amitp/gameprog.html

-Geoff

I am writing a baldur's gate style rpg(large bitmap not tiled) and finding it difficult to write pathfinding code that will stop the character from walking into an obsticle, and taking the quickest possible path.

Can anybody help me out?

Look in our AI section (in the Reference->Programming area) for some articles on pathfinding.