• A Windows service is a program configured to run on a Windows installation in the background without user interaction to perform a specific function. Although the tasks performed by these services are often important, not all of these need to remain enabled for an average user and some may be safely disabled to free system resources. However, doing so is tricky, as disabling the wrong service can lead to system instability and crashes, as well as loss of critical functionality. Several guides have been written to address this and among the most famous is the one hosted at BlackViper.com.
  
  

Distributed Link Tracking Client

• The official Windows description for this service is "Maintains links between NTFS files within a computer or across computers in a network domain." By default, it is enabled and set to automatically start with Windows. This service does not apply to the normal shortcuts but rather to logical links between NTFS files in a way that when you modify the location of one file, the link automatically updates with the new location. It is not a required feature and may safely be disabled if the user does not need such links, which is the case with most home users. On FAT32 file systems, this service serves absolutely no purpose and should definitely be disabled to save the memory it uses.
  
  

Indexing Service

• The purpose of this service as per Microsoft, is to "index contents and properties of files on local and remote computers" and to "provide rapid access to files through flexible querying language." The indexing service is notorious as a major resource hog and is usually the culprit for the slow performance of many Windows systems, since it attempts to index all the files on the system and the network, to make searching easier. An average user does not have to search for files often and thus, does not benefit much from this service. It can be safely disabled and doing so will almost certainly cause significant improvement in system performance, as suggested by Black Viper's description page for this service.
  
  

Remote Registry

• This service "enables remote users to modify registry settings on this computer," to quote its description by Microsoft. This is an obvious security hazard for most users since remote read/write access to a computer's registry could be exploited by malicious users to take over the system. The functionality was intended for system administrators to use one computer for editing the registry of all the connected computers on their network, though it is rarely used even for that purpose due to the security hazard. Black Viper calls it one of the not-needed services and strongly recommends disabling it.