SSRS filter a dataset if parameter is "Yes"

hello i have a report  as below

with date Parameters this all works fine! 

date from                date too 

01/01/2011   21/02/2013 

name        amount      date 

test1100          01/01/2012

test2        200             01/02/2013 

but what i want is to have another parameter which says something like yes or no and a filter on the data set which responds to the parameter

so that if the parameter = "yes" then filter the data set so as "not" too include test1 as a company but if "NO" then include all records! 

Steve mason