Essential open source Windows admin tool No. 12: Performance Analysis of Logs (PAL) Tool
If you've ever had a performance problem but had no idea what metrics to collect or even how to analyze the compiled data, PAL is your friend. This open source tool helps read performance monitor counter logs and analyzes them for you, using built-in thresholds that relate to the majority of your Windows products, including Exchange, SharePoint, Active Directory, and more.
PAL has been tested on Windows 7 but should also run on Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, and Windows Server 2008 R2.
Essential open source Windows admin tool No. 13: ClamWin Antivirus
This open source antivirus solution is a valuable tool for security-minded admins. ClamWin supports Windows 7, Windows Vista, Windows XP, Windows Me, and Windows 2000/98 systems, as well as Windows Server 2008 and Windows Server 2003.
The tool includes a scanning scheduler that you can use to configure appropriate scan times but does not come with an on-access real-time scanner. It also has the ability to integrate into Windows Explorer and Outlook for easy scanning.
Although it may not work as well as a commercial real-time option for virus scanning, ClamWin is certainly a worthwhile tool, especially for shops seeking a free solution.
Essential open source Windows admin tool No. 14: Virtual Router
Virtual Router is a nifty tool that turns any Windows 7 or Windows Server 2008 R2 system into a Wi-Fi hotspot.
Using Virtual Router, users can wirelessly share any Internet connection (Wi-Fi, LAN, cable modem, dial-up, cellular, and so on) with any Wi-Fi-enabled device. Laptops, smartphones, netbooks, wireless printers -- all can connect to Virtual Router just as they would any other access point, and the connection is completely secured using WPA2, the most secure wireless encryption.
Essential open source Windows admin tool No. 15: VirtualBox
VirtualBox is a must-have open source virtualization solution for any admin seeking to run guest OSes on Windows, Linux, Macintosh, or Solaris machines.
Using VirtualBox, admins can run virtual instances of a wide array of operating systems, including Windows, Linux, OpenSolaris, OS/2, OpenBSD, and even DOS. To learn more about the extent to which VirtualBox supports various operating systems as virtual machines, check out VirtualBox's guest OS wiki.