A virus or spyware can be a very harmful thing to your computer. It's always a good thing to always keep updating your operating system like Windows XP, your firewall, anti spyware, and virus scanner. To have your computer virus and spyware free you should have a Virus scanner, Spyware remover, a firewall (and Windows network connections hardware firewall enabled),  and keep updated with Automatic Updates from windows. the links below are windows updates, free virus scanners, anti spyware, and firewalls.

http://v5.windowsupdate.microsoft.com/v5consumer/default.aspx?ln=en-us  

http://www.stop-sign.com/se/se033a.php?pg=stopsign_redir%26se_spin&ver=online&n=d_mss

http://www.grisoft.com/us/us_updt7.php

http://www.symantec.com/nav/nav_9xnt/

http://www.symantec.com/sabu/nis/npf/

http://www.symantec.com/sabu/nis/nis_pe/

http://www.download.com/3001-8022-10308605.html