Here’s a freeware utility for Windows 8 Developer preview that allows you to change the background of Windows 8 metro start screen within a few clicks.
Also Check Keep Both Old Start Menu and Metro at the Same Time [Windows 8]
You don’t need to have knowledge of Windows system files to use this tool. Just download and run ‘Windows 8 Start Tweaker’ on your Windows 8 dev build and change the background of start screen to whatever you want. You can choose any image file to replace the default metro start screen background.
The tool is created by a deviant user – Ruanmei, written in C++ and the size of the tool is 103 KB only. Some instructions given by the creator of the tool are as following:
If you want the image fills out the whole screen, you should make a image by yourself. The Height of the image should be doubled with the Height of your Screen Resolution. For example, if your Screen Resolution is 1280*800, you should make a image with Height 1600, and the width is not limited.
This freeware utility also allows you to change the logon screen background color. Although, you don’t need any 3rd party tool to change the background of logon screen as it’s already been there in the general settings of Windows 8. To do so, just visit your control panel and go through ‘Personalize’ settings. However, Windows 8 start tweaker will be quite useful for those who just want to change the background of Windows 8 metro start screen without having to edit Windows files manually.