Wifi Router and Wired Modem on same PC

Hi
I am not techie so pls bear with me.

I have pc which has wired thomson speedtouch 330 modem – fully functioning.

I have a dynamode R-ADSL-C4W-G1 router. I have attached this a per the instructions. This is working.

I always turn off at mains the one I don’t wish to use.

To save me keep unplugging the phone line from one to the other I put a phone doubler in my phone socket and added both through filters to phone socket.

Is there a way to have them both switched on at the same time?

How do I tell pc which one i wish to use.

O/s windows xp