Will this ethernet "splitter" work satisfactorily?

[Josef Lowder]

.
While searching for ethernet cables to use with the hub that 
Lynn David Newton offered to give me, I came across this item: 

http://www.amazon.com/Cat5e-100base-T-Line-Splitter/dp/B000BSLXDE

Is there any reason why this simple "splitter" would not work 
to allow me to connect my two computers to my 2Wire router? 
I would only be using one at a time in any case. 

Does every computer have a separate IP address? 

Or, would it work if I just unplugged the ethernet cable from 
one computer and plugged it in to the other, moving them back 
and forth as needed?