Here are some free Microsoft software's that you maybe didn't know about and that you too might like or see a need to use. I'll add them here as a reminder for myself anyway. If you have any free Microsoft software you would like to add please make a comment.
Microsoft PowerToys for Windows XP including SyncToy (copy, move, and synchronize different directories), ClearType Tuner (tune the ClearType settings to fit your eyes the best), Open Command Window Here, Tweak UI (gives you access to system settings that are not exposed in the Windows XP default user interface, including mouse settings, Explorer settings, taskbar settings, and more), Power Calculator (you can graph and evaluate functions), etc.
Windows Defender (Beta 2) is a free program that helps you stay productive by protecting your computer against pop-ups, slow performance and security threats caused by spyware and other potentially unwanted software.
FolderShare allows you to create a private peer-to-peer network that will help you to synchronize files across multiple devices and access or share files with colleagues and friends. Share files up to 2 GB in size. No limits on quantity or size or type of files transferred.
Microsoft Time Zone conveniently runs in the system tray and allows you to easily view the date and time in various locations around the world. You can also quickly and easily add your own personal locations to customize Microsoft Time Zone the way you want.
Calculator Plus a better Calculator that also performs many different types of conversions.
Virtual CD-ROM Control Panel for Windows XP allows image files (ISO) to be mounted virtually as CD-ROM/DVD-ROM devices. Useful if you don't want to write the image to a CD/DVD-R using software's with ISO image file support. Windows Server 2003 Resource Kit includes the DVDBURN.EXE command line tool useful for writing ISO files to CD-R or DVD-R.
Tweakomatic utility that writes Windows Management Instrumentation (WMI) scripts.
Windows Deployment and Resource Kits including among many other useful tools Robocopy.exe - Robust File Copy Utility
Virtual PC to run multiple operating systems at the same time on the same physical computer. Switch between virtual machines with the click of a button.
Agent components for animated characters that can be useful in your applications. With interactive personalities in the form of animated characters you can make them move, talk, listen and react and more. I've used it for guiding users through lengthy installations using VBScript for applications like Autodesk AutoCAD and ADT.
GroupBar is lightweight desktop tool that offers enhanced window management capabilities in a Windows taskbar-like setting.
User State Migration is used to migrate user data and application configurations for a user's current client computer to a new client computer.
Windows Media Encoder including Windows Media Encoder Studio Edition and Windows Media Encoder 9 Series. Use it to capture, compress and encode audio and video content.
And much more...