Q: VPN Server Setup

I have a Win2k3 Server as the AD,DNS,and DHCP servers with the following internal IP’s 192.168.2.30 and 192.168.2.101. I need to setup a VPN server and the network is already mapped for this but the VPN server is suppose to use the .101 IP. Do I just change the .101 IP on the win2k3 server to something else?

Also, is it safe or good to the Win2k3 server as the Cert Authority server as well?

The soon to be VPN server will be running win2k3 sbs server. The IAS server will reside in the VPN server as well.

any help would be appreciated.