Back up your files externally, make your Recovery DIsks or save a backup image of the entire HD first so you have a path back to factory condition. Then wipe the HD of all code:
SSD / HDD : Optimize for Windows Reinstallation
If you have Upgrade version and wipe the HD, skip inserting the key during install and do one of the workarounds given here for installing to a wiped HD:
Clean Install with a Upgrade Windows 7 Version
If you install to wiped HD, the installer will issue a 100mb System Reserved boot partition which conveniently places the Repair Console (normally only on the DVD or Repair CD) on the F8 Advanced Boot Tools menu. So I would choose Custom Install and then Drive Options to partition as you wish and format:
Clean Install Windows 7
The installer is mostly driver-complete, with newer arriving quickly via optional Windows Updates. Just in case, have your Ethernet/Wireless driver on flash stick or CD so you can get online to Update quickly. Then enable hardware driver auto-updating:
http://windows.microsoft.com/en-US/w...-your-hardware
Any drivers then missing in Device Manager can be found on the Support Downloads webpage for your model computer or device.
Driver Install - Device Manager
Install updates and then programs slowly over time to gauge performance after each. Don't let any programs write themselves into msconfig>Startup as they slow startup, become freeloaders on your RAM/CPU and can spy on you. I only allow AV and gadgets.
Startup Programs - Change
Use a lightweight free AV like MS Security Essentials which works perfectly with Windows 7 Firewall.
http://www.microsoft.com/security_essentials/
When it is finished, clean and order the HD perfectly using state-of-the-art free CCleaner then Auslogics Disk and Registry defraggers monthly.
CCleaner - Free software downloads and software reviews - CNET Download.com
Auslogics Disk Defrag - Reviews and free Auslogics Disk Defrag downloads at Download.com
Auslogics Registry Defrag - Free software downloads and software reviews - CNET Download.com
Then save a Windows 7 Backup image externally so you never have to reinstall again, just reimage the HD or replacement using DVD or Repair CD.
Backup Complete Computer - Create an Image Backup