Change homepage after installing IE7 via IEAK

Hi all, I have used the IEAK in the past to install IE7 on our systems. We
have recently changed the server on which our IE homepage is stored. I have
created a new policy for future IE7 rollouts but I was wondering what to do
with those already rolled out.

I have changed the homepage location using Group Policy but it does not seem
to be having an effect. I would have expected GP to take precedence over any
settings created with the IEAK ??

Do I need to re-install my new version of IE7 on each machine, or is there a
CMD I can run or policy I can set in GPMC to make GP take precedence?

Thanks in advance,

Martin