On 12. August 1981 IBM presented in New York the first Personal Computer - IBM 5150 -. It's the Grand Dad of all PC's nowadays.
Leading officials at IBM didn't believen in the success of that concept, but IBM CEO Frank Cary didn't want to share the market with Apple or Commodore.

To improve the development of the PC, IBM-developers bought lot of components from other companies - like the operating system of an unknown developer called Bill Gates.

Details:
http://en.wikipedia.org/wiki/IBM_Personal_Computer

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The Creeper virus was first detected on ARPANET, the forerunner of the Internet in the early 1970s.[3] Creeper was an experimental self-replicating program written by Bob Thomas at BBN in 1971.[

A program called "Rother J" was the first computer virus to appear "in the wild"

The first PC virus in the wild was a boot sector virus dubbed ©Brain, created in 1986 by the Farooq Alvi Brothers, operating out of Lahore, Pakistan, reportedly to deter piracy of the software they had written[citation needed]. However, analysts have claimed that the Ashar virus, a variant of Brain, possibly predated it based on code within the virus.[original research?]
http://en.wikipedia.org/wiki/Computer_virus

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