try going here it will perform a scan and tell you if you have file or print sharring enabled.

if you dont need it then i suggest shutting it off by using this -> http://www.grc.com/files/noshare.exe

more information on port 139 (windows file & printer sharing) can be found here

I also suggest getting a firewall - i use outpost and have always found it good...they do a pro version or a free version (also has built in ad-blocker) get either of them from here -> http://www.agnitum.com/products/outpost/

v_Ln