In a word, no..get a firewall as suggested..also kee Windows up to date
You might want to give these programs a shot too:
1.Spybot S&D:http://www.safer-networking.org/en/index.html
2.CWShredder:www.softpedia.com
3.Swatit:http://swatit.org/
4.TheCleaner:www.moosoft.com
The last two're trojan cleaners,CWShredder's meant for browser hijacks and such and Spybot's meant for spyware..hope this helps