Changing network address

I have recently inherited administration duties for a
Windows 2003 Server with 2 NIC's, one on the Internet,
one on the LAN.

It's the only DC for the LAN, and also provides NAT,
DHCP, and Remote Access

To resolve some VPN client routing issues I have no
control over, I want to change the internal network
address from 192.168.0.0 to something else, say
192.168.199.0...
Since this is the only DC on the network, I'd like to be
confident the change will go quickly before I start, and
that everything (AD, DNS and DHCP) will still work when
I'm done.
My major concern is how this will affect the AD
integrated DNS zones... will they require any manual
reconfiguartion?
If anyone has gone through this procedure, I'd appreciate
you input.

Thanks