There are many websites, where you can find Keyboard shortcuts for windows users. So I just though t why not to put it in our blog too Here are few essential keyboard shortcuts that you will need in day to day life.
Most common Keyboard Shortcuts:

1. Windows key + R = Run menu
2. cmd = Command Prompt (open run menu then type cmd)
3. iexplore + "web address" = Internet Explorer  (under run menu. Ex: iexplore “www.aliencoders.org”)
4. CTRL + Shift + Esc = Task Manager (ctrl + alt +del may do the same thing but its specific one)
5. Windows key + Break = System properties
6. Windows key + F = Search (I have installed Ava Find for this purpose ;P )
7. Windows key + D = Hide/Display all windows
8. Ctrl + H = Opens the history bar  (for browsers)
9. Ctrl + C = Copy
10. Ctrl + X = Cut
11. Ctrl + V = Paste
12. Ctrl + Z = Undo
13. Ctrl + A = Selet All
14. Alt and Esc = Switch between running applications
15. Alt + Tab = switch through opened items (you can toggle here)
16. Try windows key + tab (in windows vista it shows all running  application in 3-d style)
17. Ctrl + Esc = Program Menu
18. Del = deletes the selected item (will be there in recycle bin if size is not more than 2 GB  approx.)
19. Shift + Del = deletes selected items permanently
20. Alt +F4 =  Close the active item, or quit the active program.
21. F2 = renames selected item(s)
22. F4 = Display the Address bar list in My Computer or Windows Explorer.
23. F5 = Refresh the active window.
24. WIN Key+D = Shows the desktop.
25. WIN Key+M = Minimizes all windows
26. WIN Key+Shift+M = Restores minimized windows.
27. Windows key + L = to lock your computer or to switch over other user

Note:  pressing SHIFT when you insert a CD into the CD-ROM drive will  Prevent the CD from automatically playing. There are  few commands which you can use after open run menu (win key + R):

1. devmgmt.msc = Device Manager
2. compmgmt.msc  = Computer management
3. msinfo32 = System Information
4. cleanmgr = Disk Cleanup
5. mmc = Microsoft Management Console
6. excel = Microsoft Excel (If Installed)
7. msaccess = Microsoft Access (If Installed)
8. powerpnt = Microsoft PowerPoint (If Installed)
9. winword = Microsoft Word (If Installed)
10. notepad = Notepad
11. wordpad = WordPad
12. calc = Calculator
13. mspaint = Microsoft Paint
14. wmplayer = Windows Media Player
15. rstrui = System Restore
16. control = Opens the Control Panel
17. control printers = Opens the Printers Dialog
18. mstsc = Remote Control window
19. conf = to start net meeting (works in win XP, does not work in Vista and Win7)

For more details visit here: