Migrate SBS 2003 to 2008 in Home Network environment

Hi Experts

I am migrating an SBS 2003 server to an SBS 2008 server for a client at his home. I don't have any experience of doing work with servers so need some help...

The setup is a home network with a wireless router (BTHomeHub) running the DHCP server and serving up IP addresses to all the various PCs and wireless devices in his home. The PCs are part of a workgroup (not a domain).

His SBS Server connects directly to the router and runs Exchange and Sharepoint. He uses these to manage his emails and a shared document store respectively.

He connects to the server from his PCs using Terminal Services.

His existing server is on its way out so he has bought a new one and an SBS 2008 license and has asked me to migrate Exchange and Sharepoint to the new server running SBS 2008.

I have read up on migrating SBS 2003 to SBS 2008 and understand that on the SBS 2003 server I need to reduce the network adapters to a single one (there are currently two) and I need to disable the DHCP server at the router. The SBS 2003 has DHCP running but looks like its scope is for internal devices/functions.

My questions are:

Should I go ahead and turn off the DHCP server at the router so that the SBS 2003 server serves up IP addresses to the various home PCS and wireless devices? Will the PCs and devices connect OK or will I need to add them to the SBS 2003 domain? Or is there a better way to do this - e.g. preserve the home network (i.e. the router continues to serve up IP addresses to all devices) and have the SBS 2008 server (once I have migrated to it) connect to the router and sit in its own little domain (as the SBS 2003 server currently does).

Any suggestions gratefully received.

Thanks