Expanding home network

I've recently moved into a shared house and want to share BT broadband
between 2 PCs and a laptop.

Connected to the BT router I have a Netgear R0318 Cable/DSL router with
a wireless transmitter plugged in.
My laptop works fine as it was all configured like this at my previous
address.

Unfortunately I don't know the admin password or encryption key for my
own router and I want to add 2 more PCs to access the internet in the
same way.

I'm thinking that the simplest solution might be to reset the router to
its factory settings, start afresh and use the XP wizard to set up a
new home network for all 3 of us.

Also not sure what to do about IP addresses

All help gratefully received.
Many Thanks
Esme