List of Best and free Software, Utility and Tool for System Administrators

Process explorer

Process monitoring tool for windows operating systems, unlike task manager it provides vast amount of information for running process and  detailed information on DLLs, threads, handles and TCP/IP connections. It is a advanced process management utility and replacement for task manager

Link : http://technet.microsoft.com/en-in/sysinternals/bb896653.aspx 

Belarc Advisor 

A 3402 Kilo Bytes file size of free tool to do your system inventory . The software builds a in-depth profile of installed hardware and software, network, Installed hotfixes, status of anti-virus , you can use your Web browser to view the details.

• Works with Operating systems:  Server (Both 32 and 64 bit) : Windows server 2012, 2008, 2003 Windows 8, Windows 7, windows 2008 R2,  Windows Vista, Windows server 2008, Window server 2003, XP, 2000, NT 4, Me, 98, and 95. Both 32-bit and 64-bit Windows are supported.
• Works with browser Versions : Internet Explorer, Firefox, Safari, Opera, and others.

Link : http://www.belarc.com/free_download.html

Norton removal tool

Tool is used to  uninstall Norton AntiVirus, Norton Internet Security, Norton 360, and Norton SystemWorks 12.0 from your computer. If you use ACT! or WinFAX, back up those databases before you proceed.

Link : http://support.norton.com/sp/en/in/home/current/solutions/kb20080710133834EN_EndUserProfile_en_us/
MyDefrag-4.0 

Completely automated and easy to use, quick, low overhead, with several optimization strategies, and also works for floppies, USB disks, memory sticks, and anything else that looks like a disk to Windows. It is a simple tool which can defragment and optimize the windows 2000/2003/XP/Vista/2008/X64.

Comes with different versions as below

• JkDefrag.exe - Windows Version
• JkDefragCmd.exe - Commandline version
• JkDefragScreenSaver.scr + JkDefragScreenSaver.exe -Screen saver version.

Link: kessels.com

PING [Partimage Is Not Ghost ] 

Best tool for Linux system rescue and windows with the below features

• Backup and restores Locally or network files and partition
• Can be used to backup Bios and restoration bootable DVD 
• Backup MS Network Shared directory, NFS, FTP or SSHFS 
• Creates bootable DVD
• Partitions and Format a disk for installing Windows 

Link: http://ping.windowsdream.com

SuperScan

A vigorous utility known as  SuperScan is a TCP port scanner, which also includes list of other additional networking tools like ping, traceroute, HTTP HEAD, WHOIS and many more. Can be used to perform ping scans and port scans for any IP range or specify a text file to extract addresses from. Other features include TCP SYN scanning, UDP scanning, HTML reports, built-in port description database, Windows host enumeration, banner grabbing and more.

Download link: http://www.snapfiles.com/get/superscan.html

Windows Sysinternals 
Provides a list utilities useful to troubleshoot, manage, and diagnose your Windows systems and applications.
Links : http://technet.microsoft.com/en-us/sysinternals/default.aspx

VirtualBox

Free Open source server, desktop virtualulization utility from Oracle 

• List of Supported host operating systems : Linux, Mac OS X, Windows XP, Windows Vista, Windows 7, Windows 8, Solaris, and OpenSolaris; there is also a port to FreeBSD.[3] 
• List Supported guest operating systems :  versions and derivations of Windows, Linux, BSD, OS/2, Solaris and others. The release 3.2.0, VirtualBox allows to virtualize  Mac OS X guests on Apple hardware, OSX86 can also be installed .

Download Link: virtualbox

Everything from Voidtools

It is a simple, easy to use and free utility . Shows faster and  better search results as compared to  the built in Windows search.  An administrative tool to locates files and folders by filename for Windows. It is a Freeware

Works with Operating System : Windows 2000, XP, 2003 and Vista and Windows 7

Drawbacks of using : Only search local Files and folders and Removale NTFS volumes. To search for Netwok drive you need to install it on both local and network computers and start ETP server, does not search contents it  only works for files and folders names

Link : http://www.voidtools.com

WinDirStat and KDirStat

WinDirStat is a disk monitoring and clean up utility for Windows operating systems. On loading it takes a while to read the complete directory tree once and then presents it in three useful views:

The directory list sorts like Windows Explorer but it is sorted by file/subtree size

The treemap displays complete contents of the directory tree

The extension list, Display statistics about the file types.

KDirStat is a GUI () disk usage utility for Linux, BSD, and  other Unix-type systems like Solaris. it provides cleanup facilities to reclaim disk space.

Download Link: http://windirstat.info/

Download Link: http://kdirstat.sourceforge.net/

Wireshark 
A very popular, free and open source tool used for Network troubleshooting  It capture the packets from Network traffic which is helpful in troubleshooting purpose i network related issues. Network Administrator's read the live packet capture or can also save the capture.
Compatible with  Linux, OS X, BSD, and Solaris and Microsoft Windows.
Link: http://www.wireshark.org/

UltraTech Knowledgebase Viewer
UltraTech Knowledge base viewer provides  list of  tools and their links. It has list of  KB CONTENTS, not well updated but good for the beginner who are looking for good technical links
Link: http://kb.ultratech-llc.com