Dell techs had me buy new Windows 7 OS disc, which I installed yesterday. Just a few minutes ago, a phone call came in saying they were calling from Microsoft and wanted to run a free scan since I had bought a Microsft product. They had me download teamviewer.com software, malware, ccleaner, superantii spyware. They ran scans and said I was infected and I should buy these software packs for $79. Is this a real Microsoft service? I still have these softwares on my computer, should I delete them? What other threats may be present if this is not a real Microsoft service?