My first problem i've needed to post:

I've created a basic head using polygons and i'm now rigging it for facial expressions. I've seen a load of tutorials where whilst they are rigging characters they switch between half the poly character and the full subd character and i can't for the life of me find anywhere on the net that shows me how to do this.
I am rigging it with half of the head (as below) and when i built the head i used a connect poly script to mirror it in the x direction and merge all the vertices - it worked fine.
i assumed whilst rigging i could just use this script to mirror the head and see how he is looking, but it will no longer mirror it.

what i am essentially asking is:
What is the standard way whilst rigging with half a head to have the rig apply to a mirrored side of the head?

this tutorial guuy was just clicking buttons and the subd model would appear, mirrored and rigged the same as his half head, or he could just switch to the low poly model again.

I am willing to start the rigging again, i just want to know the correct way to do this so at the end of the rigging i have not just half a head!

Nay help would be great!, thanks