These utilities are from Microsoft and are very handy. they belongs to the following categories
Sysinternals Suite
The entire set of Sysinternals Utilities rolled up into a single download.
AccessChk
This tool shows you the accesses the user or group you specify has to files, Registry keys or Windows services.
AccessEnum
This simple yet powerful security tool shows you who has what access to directories, files and Registry keys on your systems. Use it to find holes in your permissions.
AdExplorer
Active Directory Explorer is an advanced Active Directory (AD) viewer and editor.
AdInsight
An LDAP (Light-weight Directory Access Protocol) real-time monitoring tool aimed at troubleshooting Active Directory client applications.
AdRestore
Undelete Server 2003 Active Directory objects.
Autologon
Bypass password screen during logon.
Autoruns
See what programs are configured to startup automatically when your system boots and you login. Autoruns also shows you the full list of Registry and file locations where applications can configure auto-start settings.
BgInfo
This fully-configurable program automatically generates desktop backgrounds that include important information about the system including IP addresses, computer name, network adapters, and more.
BlueScreen
This screen saver not only accurately simulates Blue Screens, but simulated reboots as well (complete with CHKDSK), and works on Windows NT 4, Windows 2000, Windows XP, Server 2003 and Windows 9x.
CacheSet
CacheSet is a program that allows you to control the Cache Manager's working set size using functions provided by NT. It's compatible with all versions of NT.
ClockRes
View the resolution of the system clock, which is also the maximum timer resolution.
Contig
Wish you could quickly defragment your frequently used files? Use Contig to optimize individual files, or to create new files that are contiguous.
Ctrl2cap
This is a kernel-mode driver that demonstrates keyboard input filtering just above the keyboard class driver in order to turn caps-locks into control keys. Filtering at this level allows conversion and hiding of keys before NT even "sees" them. Ctrl2cap also shows how to use NtDisplayString() to print messages to the initialization blue-screen.
DebugView
Another first from Sysinternals: This program intercepts calls made to DbgPrint by device drivers and OutputDebugString made by Win32 programs. It allows for viewing and recording of debug session output on your local machine or across the Internet without an active debugger.
DiskExt
Display volume disk-mappings.
Diskmon
This utility captures all hard disk activity or acts like a software disk activity light in your system tray.
DiskView
Graphical disk sector utility.
Disk Usage (DU)
View disk usage by directory.
EFSDump
View information for encrypted files.
Filemon
This monitoring tool lets you see all file system activity in real-time.
Handle
This handy command-line utility will show you what files are open by which processes, and much more.
Hex2dec
Convert hex numbers to decimal and vice versa.
Junction
Create Win2K NTFS symbolic links.
LDMDump
Dump the contents of the Logical Disk Manager's on-disk database, which describes the partitioning of Windows 2000 Dynamic disks.
ListDLLs
List all the DLLs that are currently loaded, including where they are loaded and their version numbers. Version 2.0 prints the full path names of loaded modules.
LiveKd
Use Microsoft kernel debuggers to examine a live system.
LoadOrder
See the order in which devices are loaded on your WinNT/2K system.
LogonSessions
List the active logon sessions on a system.
MoveFile
Allows you to schedule move and delete commands for the next reboot.
NewSID
Learn about the computer SID problem everybody has been talking about and get a free computer SID changer, NewSID.
NTFSInfo
Use NTFSInfo to see detailed information about NTFS volumes, including the size and location of the Master File Table (MFT) and MFT-zone, as well as the sizes of the NTFS meta-data files.
PageDefrag
Defragment your paging files and Registry hives.
PendMoves
Enumerate the list of file rename and delete commands that will be executed the next boot.
PortMon
Monitor serial and parallel port activity with this advanced monitoring tool. It knows about all standard serial and parallel IOCTLs and even shows you a portion of the data being sent and received. Version 3.x has powerful new UI enhancements and advanced filtering capabilities.
Process Explorer
Find out what files, registry keys and other objects processes have open, which DLLs they have loaded, and more. This uniquely powerful utility will even show you who owns each process.
Process Monitor
Monitor file system, Registry, process, thread and DLL activity in real-time.
ProcFeatures
This applet reports processor and Windows support for Physical Address Extensions and No Execute buffer overflow protection.
PsExec
Execute processes with limited-user rights.
PsFile
See what files are opened remotely.
PsGetSid
Displays the SID of a computer or a user.
PsInfo
Obtain information about a system.
PsKill
Terminate local or remote processes.
PsList
Show information about processes and threads.
PsLoggedOn
Show users logged on to a system.
PsLogList
Dump event log records.
PsPasswd
Changes account passwords.
PsService
View and control services.
PsShutdown
Shuts down and optionally reboots a computer.
PsSuspend
Suspend and resume processes.
PsTools
The PsTools suite includes command-line utilities for listing the processes running on local or remote computers, running processes remotely, rebooting computers, dumping event logs, and more.
RegDelNull
Scan for and delete Registry keys that contain embedded null-characters that are otherwise undeleteable by standard Registry-editing tools.
RegHide
Creates a key called "HKEY_LOCAL_MACHINE\Software\Sysinternals\Can't touch me!\0" using the Native API, and inside this key it creates a value.
RegJump
Jump to the registry path you specify in Regedit.
RegMon
This monitoring tool lets you see all Registry activity in real-time.
RootkitRevealer
Scan your system for rootkit-based malware.
SDelete
Securely overwrite your sensitive files and cleanse your free space of previously deleted files using this DoD-compliant secure delete program.
ShareEnum
Scan file shares on your network and view their security settings to close security holes.
ShellRunas
Launch programs as a different user via a convenient shell context-menu entry.
Sigcheck
Dump file version information and verify that images on your system are digitally signed.
Streams
Reveal NTFS alternate streams.
Strings
Search for ANSI and UNICODE strings in binaryimages.
Sync
Flush cached data to disk.
TCPView
Active socket command-line viewer.
VolumeId
Set Volume ID of FAT or NTFS drives.
Whois
See who owns an Internet address.
WinObj
The ultimate Object Manager namespace viewer is here.
ZoomIt
Presentation utility for zooming and drawing on the screen.
You can download them from Microsoft Technet