Windows 8 supports two new ways to revert your system to an earlier state.  From the Settings charm, access More PC settings and then click General.  Towards the bottom, you’ll see these two choices:

1. Refresh your PC without affecting your files.  This choice keeps your personal data, system settings, and Metro style applications.  Desktop applications will be removed, unless you create a custom image as I detail below.
2. Reset your PC and start over.  This choice is like a factory reset.  All of your personal files, Metro style apps, and Desktop apps will be removed.  You can optionally write random data to your drive for added security.

Use option 2 if you’re going to sell or give away your system.  All of your personal files will be erased.  The rest of this post is about option 1.

Option 1, refreshing your PC, keeps your personal data and reinstalls Metro style applications.  Desktop apps will be removed, and their names will be placed in a file on your desktop called Removed Apps.

Reinstalling all of your Desktop apps can be time consuming, so Windows 8 offers a command called recimg.exe to make this easier.  recimg creates an image which is used by the refresh facility when restoring Windows.  Not only will your personal data and Metro style apps be saved, but so will Desktop apps you have installed at the time you create the image.  This can save you a lot of time.

After installing Windows 8 on a new system, the first thing I do is install Visual Studio and Office.  I then do this as Administrator:

mkdir C:\RefreshImage
recimg /CreateImage C:\RefreshImage
recimg /ShowCurrent

Refreshing my PC will then preserve my Desktop apps.  Any Desktop apps I install after creating the image will not be copied over to the refreshed system.  However, the old system is preserved in C:\Windows.old.

For more information, run recimg /help. Also read the Refresh and reset your PC article by Desmond Lee on the Building Windows 8 blog.