Update, October 21, 2013:This post was updated to reflect a change in the description of the setting, in the final release of Windows 8.1.
The Windows 8 Start screen is a good starting point for Windows 8 devices with touch screens, but on PCs with standard screens, you might prefer to boot directly to the desktop. Previously, you could bypass the Windows 8 Start screen with Start8, but Windows 8.1 now lets you do it natively. Here's how:
Step 1: Right-click on the Windows 8.1 taskbar, then choose Properties.
Step 2: Click on the Navigation tab, then under the Start screen section, check the box next to "When I sign in or close all apps on a screen, go to the desktop instead of Start."
The next time you boot Windows 8.1, you'll go straight to the desktop without ever seeing the Start screen.