Windows 7- Reinstallation

Following on from gregrocker's excellent advice, a clean install could take several hours depending on how long it takes to complete updating and installing your own programs, and then the system image backup.

I don't quite know how you've got it into your head that changing to another user account will speed up your computer - it won't.

Look at it this way, if your car is performing badly, it doesn't matter which door you use to get into it and drive it, its performance is still poor.

If you want to speed up your computer, gregrocker's method is the way to go. :)

Shouldn't take more than an hour to reinstall the OS if you spread the Updates and Program installs over subsequent days as suggested to monitor performance changes better.