Remove the audio from a video:  To remove an unwanted audio or a background sound from a video, import the video into Windows Movie Maker, go to the timeline mode, right click on the white line in the “Audio” region and choose the “Mute” option.

Change the speed of the audio or video. To increase/decrease the speed at which audio/video plays in Windows Media Player, you can go to the menu bar and select Now PlayingàEnhancements à Play Speed Settings

Send large files (of about 1-2 GB) with ease: Web sites like yousendit.com, transferBigfiles.com, send6.com etc enables you to send huge files, including large audio and video files across the net in 10-20 minutes. However, if you want to use the service freely, the file size is limited to approximately 100 MB in many of these sites.

Convert files:  To convert any files from one format to another in minutes, you can use the software at the website Zemzar.com. Here, free service is available for files up to 100 MB. Also, Media-convert.com and youconvertit.com are 100% free media conversion sites.

Get Complete System Information: Type MSINFO32 in the “Run” dialog box and you would get the complete hardware information regarding your computer. Similarly, to find out the IP address of the computer (in case it is connected to the net), you can go to Settingsà Network Connections à Local Area Connection (or just type ‘ipconfig’ at the Command Prompt) 

Make the Desktop icons smaller:  To make the icons on the desktop smaller, simply right-click on the Desktop area and select the “Classic View”, or select one of the icons and press the “Ctrl” button on the keyboard.

Minimise all applications with a single keystroke: The keystroke ‘Windows’ icon + ‘D’ automatically minimises all the open applications. It is similar to the “Show Desktop” icon on the taskbar. Similarly, pressing the ‘Windows’ icon + E opens up the Windows Explorer/My Computer.