Alcatel ST Pro Network IP Configs

Ok, so basically I have the Alcatel Speed Touch Home, and plan on upgrading it to a 'Pro' model following this guide. The modem and all node PCs will be connected via a switch. The modem has a default IP address of 10.0.0.138, and the guide says that all PCs on the network should have an IP address in the form of 10.0.0.x - is this necessary? Can I give them 'standard' IP addresses (192.168.0.x) and just configure the gateway as 10.0.0.138 - wouldn't this be enough?

Also, at the moment I have the modem ('Home' version) connected to a single PC through an ethernet NIC. When the technician came to set it up he installed Microsoft VPN Support, and I somehow connect to the internet through this. How does this work? (You can just link me to an explanation somewhere) Also, when I re-setup the network with the switch and everything, should I remove this VPN support?

Thanks,
John C.

[wizbones]

Yes you will need to change all your IP's to the 10.0.0.x range so it will all work.  

VPN stands for Virtual Private Network. If they've installed this and this is what you connect through a Virtual Tunnel so to speak then you will need to leave this in place.