Ok heres what you wanna do to stay safe when you or line If your on cable or dsl get a firewall ( zonealram - sygate - outpost ) they are all free and are worth the download ,next make sure you have a antivirus program and update it regularly , those are your two most important programs to have running . next you should disable file and printer sharing this is done by going to Start > control pannel > network connections > right click on your current connection ( dailup or dsl/ cable) select properites uncheck file and printer sharing click ok your done if you want to see what ports are open on your pc i would suggest going to
http://grc.com/intro.htm click on the Sheilds up link and follow those instuctions
also here are some links to firewalls and a free av
Sygate -
http://soho.sygate.com/default.htm
Outpost-
http://www.agnitum.com/download/outpost1.html
Zone Alarm -
http://www.zonelabs.com/store/conten...ap_za_grid.jsp
free Anti virus -
http://www.grisoft.com/us/us_dwnl_free.php
here are some places to scan your pc free online for trogans
http://scan.sygate.com/
http://www.wilders.org/free_services.htm