Rajesh, I would recommend buying a copy of SnagIt 8.1 developed by Techsmith. Though SnagIt costs around $40, it's worth every penny and packed with an impressive array of features including support for Flickr and Skype. [read detailed review]
But if $40 sounds too big an amount for a task like screen capture that can even be done by pressing the PrintScreen key, here are some of our other favorite screen grabbing software that are both freeware and lightweight [their installers are less than a MB in size].
Snippy - this tiny screen capture utility sits like a scissor icon in your Windows Tray. When you click the icon to capture any area of the screen, the mouse cursor changes to a pen. You then mark any irregular area of the screen and it is automatically copied in the Windows clipboard. For capturing rectangular portions, press the shift key while dragging the mouse. Download Snippy
FastStone Screen Capture - this is a feature rich screen capture software free for personal use. Like other commercial software, FastStone lets you capture anything on the screen including window regions, menus, icons, freehand-selected regions and even scrolling windows/web pages. The program supports multiple monitor screens, annotation tools and can output the capture to any of the image formats or to your favorite image editor.
Screen Hunter - This utility has both a free and pro version though the former should satify most of your screen-capture needs. ScreenHunter is recommened when you have to take multiple screenshots consecutively - the program would automatically name your files and save them in one folder. The zoom feature lets you capture rectangles with visual highlight and great accuracy.
GadWin PrintScreen - While you can only capture either the full computer screen or just the active window, the advantage of Gadwin is that it can capture the mouse pointer and you also get to choose the destination of your screenshots [like Windows clipboard, printer or even a file]. Gadwin also support time-delay captures which are useful while capturing submenus. Download Gadwin
101 Clips - A multi-clipboard program that runs miniumed in your system tray and captures everything from the clipboard as you cut or copy from other programs. It keeps the last 30 clips. When you want to paste one back, all you have to do is restore it and click on the clip you want. Supports Windows Vista.
Which is the best screen capture program for me ? - It depends on your need - if you are:
looking to capture irregular areas of your screen - Snippy
looking for lot of features including auto-scrolling - FastStone
looking to capture tons of screenshots - ScreenHunter
looking for a decent Microsoft Office Clipboard replacement - 101 Clips
• Capture screenshots of webpages inside Web Browser
• Screencasting - Capture Movies of your Computer Activity