I know I should read my manual clearly, but Im not a "techie". COntacting the manufacturers sites for examples isnt much of a help.

I have downloaded several videos and songs from the internet. I felt that the computer’s speed is getting slower. I thought that it was a virus. With the help of avast anti virus I detected the viruses that was incurred in the computer. Later I found that the computer is free of any viruses. I don’t know that still my PCs speed is slow. Am I mistaken that my PC is free of viruses or there are other dangers as well? Please help me as soon as possible!