Ultimate Windows Tweaker by The Windows Club is a freeware utility that works for all editions of Windows 7. Rainmeter is a free, open source utility that lets users customize the desktop. Advanced users can also tweak various Windows 7 settings using in-built utilities, such as Regedit.
The Ultimate Windows Tweaker utility provides over 150 settings for Windows 7, including performance tweaks, extra security settings, and context menu customization options. Rainmeter focuses more on providing customizable skins and visual tweaks for the Windows desktop.
There are various Windows tweaks individuals can do using only built-in utilities. For example, PCWorld.com has an article that details six registry edits that can improve Windows 7 performance. However, using tools such as Regedit can cause computer problems if the user makes a mistake.