Needed/Unneeded files

Tech-Archive recommends: Speed Up your PC by fixing your registry

Did a virus scan- found trojan horses in files "c:\counter.cab:\counter.exe"
"c:\counter.cab" "system volume information\restore" The antivirus program
asked if I wanted to delete these files. What are these files & do I need
them, or can I safetly delete these? I don't have a clue on what to do.
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