Need to convert the existing doc/xls to PDF using c#

Question

hi need to show the xls/doc in the webpage i.e inside the webpage like IFRAME. user will give the path of the documents in the textbox above iframe. I am trying to convert the existing  docs/xls into PDF using c# to get the doc from path given by user and need to show in iframe.
can you give me the code or free 3rd party tool to achieve this. kindly help bit urgent.
 
 
[email protected]