I bought a laptop just over a year ago with a subscription to McAfee already installed.  The OP is Vista Home Edition.  I find that McAfee and 'Windows Defender'  are often scanning at the same time.  Is this necessary, and if not, why did Dell install 2 Virus applications?

Also, it takes McAfee 5 DAYS to complete a scan, whether or not Defender is scanning at the same time.  This causes problems if Windows Update decides to restart the computer before McAfee has completed the scan.  Why is McAfee taking so long when the laptop is not my main PC and I don't have many files on there?