After lurking around in this forum, I've learned that it's best to have only 1 of anti virus and 1 of anti spyware install on the computer. But I saw all of this program being installed on my daughter PC; Nod32, Spybot-Search & Destroy, HijackThis, Ad-Aware, (SmitfraudFix, VundoFix, these two were installed recently to get rid of trojans, should I uninstalled them?) and Error Repair Professional.
I feel like it's too much but need some more advice and opinion from someone who know better. Plus, then i can use your advice to teach my daughter, too)
Have a Great Day!
NancyWell from my experience it is best to have more than one of each. They each look for DIFFERENT fingerprints of viruses and spyware, some look in every file and folder on a hard drive, some just look in the most popular places. In all honestly there's no WAY to be 100% protected from viruses or spyware unless you completely unplug your computer from the internet, but the next best thing to have more than one line of defense. To speak for myself I have Spybot Search and Destroy, AdAware, Windows Defender, and HijackThis for adware, and although I should have another anti-virus (sometimes more than one don't play well together) I'm using the free AVG Anti-Virus, there's ALSO a web-based virus scan from TrendMicro.com. Another point I feel I should make is that you need to make sure you keep them all updated. Most of them have some sort of automatic update as well. Hope this helps some. It is never suggested to use more than one antivirus. It will LEAD to problems including false positives, blue screens and system crashes. They conflict with each other.

Using more than one on DEMAND spyware scanner is advised. But only one that has real time protection as you will get the same problems.

Same for firewalls.Thank you for clearing this up.