im trying to write code for picking one of a number of objects on the screen. when i then try to move or change the picked object all the objects seem to move as if they were all picked. What am i doing wrong? is there some different way i should set up my objects?

Any transformation you do is affecting everything you draw, until you reset the transformation again.

What you need to do is to apply the transformations on the specific object only, and restore the transformation when you are done with that object. Use glPushMatrix and glPopMatrix to save and restore transformations.