Have spent the morning on and off trying to find a solution to this, but no go.

What I'm trying to do:
I want to creat a bootable CD that re-images a computer using ghost. This I have and it all works great.
But I now need to add a restriction, I need this CD only to be good until a certain date, after which it just does nothing.

Plan of attack:
Compare todays date with the best before date, but how todo this in a DOS enviroment?

Help!