2.5 : Update script on frame change, how?

I’m trying to write a script that will indicate what frame you’re on.
How do I update the text object when the frame number changes( without creating multiple objects)?

###### Current Question: How do I update this script when the frame changes? 

import math

frame =bpy.data.scenes[0].frame_current

#FrameDisplay will update a text object based on the current frame
def FrameDisplay():
    bpy.ops.object.text_add(view_align=False, enter_editmode=True, location=(0.0, 0.0, 0.0), rotation=(90*d, 0.0, 0.0))
    for c in str(frame): bpy.ops.font.text_insert(text=c)
    bpy.ops.object.mode_set(mode='EDIT', toggle=True)

# this is the method call

If you know how to update based on a frame change , that would be great!