Sorry to say this but skunx710 is right !! If you don't at least have SP1 then you are leaving yourself open to Viruses & hacker's & spyware....
The reason for SP1 & SP2 is to plug up any of the security risks that are left open by Windows....Microsoft knew that it's OS were vulnerable, that is why they came out w/these patches & fixxes.
Also, i would go to Window's update: And D/L the critical updates for your operating system...And do it , behind a firewall....