Downloading TweakUI 2.20 from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this software available. The program lies within System Utilities, more precisely System Optimization.
This free tool was originally developed by Microsoft. The latest version of the program can be installed on PCs running Windows 2000/XP/XP Professional/Vista/7/8/10/11, 32-bit. TweakUI is sometimes referred to as "Tweakui Powertoy for Windows XP", "TweakUI XP", "TweakUI for Windows 64-Bit".
The common filenames for the program's installer are tweakui.exe, DVDMaker.exe, TweakUI64.exe, tw.exe or TaskSwitch.exe etc. We recommend checking the downloaded files with any free antivirus. The most popular versions of the tool are 2.2, 2.1 and 1.0.
From the developer:
TweakUI amp up Windows XP with a PowerToy that changes the default user interface. The program is designed for advanced computer users only. Tweak UI allows you to customise the user interface of the Windows operating system. Users with older, slower computers can turn off many aspects of the operating system's eye candy, such as fading menus, drop shadows, and cursor shadows.
You may want to check out more software, such as Notebook Hardware Control, RegAlyzer or RegistryFix, which might be similar to TweakUI.