1) Remove any existing Anti virus software and download and install 'Microsoft Security Essentials'
http://windows.microsoft.com/en-IE/windows/security-essentials-download​​

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2) Download and install 'CCleaner'. CCleaner cleans up junk files and invalid registry entries allowing Windows to run

considerably faster.
http://download.cnet.com/CCleaner/3000-18512_4-10315544.html

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3) Within the Windows 7 Control Panel, 'Check for performance issues'.
http://windows.microsoft.com/en-ie/windows7/optimize-windows-7-for-better-performance