If your system performance starts deteriorating or software starts conflicting then you have a problem. In short you should have one firewall, one antivirus, and at least one anti-spyware utility. Free options are ZoneAlarm Basic firewall, AVG FREE or Avast Home antivirus, Windows Defender, and Ewido. (I'd recommend having all four installed and performing weekly scans. Aside from that, use Firefox instead of Internet Explorer...Microsoft's browser is simply too insecure and prone to attacks.
Hope this helps,
I have a emachine with xp installed when I purchased the computer. I've had it almost 3 years come feburary. My question is can you have to much spyware,adware,antivirus protection. Each system that I download tells me a differant thing. I also have window washer an the cleaner downloaded. On window washer I have never bleached any thing afraid I mite delete something important. I dont recieve any auto up grades any more don't know if microsoft just stops sending them an I have to reregister or what? Can some one help? Thanks Puffmomma