Shortcut to Lock your Workstation.

Apart from using Windows+L, try something else to lock your window. Just Double-Click On the Desktop, Right-Click> New> Shortcut>

In the 'location of the item' , Type in - rundll32.exe user32.dll,LockWorkStation

Give it a name you want and click Finish

That's it !

Now, whenever you want to Lock your system just double-click the shortcut
Enjoy!

Lengthen Outlook Mail Notifications

I don't know of any way to make the new-mail pop-up halt the screen saver. Your best bet is to set the Desktop Alert to stay visible long enough that it will still be there when you return to the computer. Outlook limits the alert duration to 30 seconds, but a Registry tweak can set it for much longer. 

Launch Regedit from the Start menu's Run dialog and navigate to the key :

HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Common\DesktopAlert Look in the right-hand pane for a value named TimeOn. It probably won't be there; in that case, right-click in the right-hand pane, choose New | DWORD value, and name the value TimeOn. Now double-click it and click the Decimal option. Type in a value equal to the number of milliseconds you want the alert box to remain visible. There are 86,400,000 milliseconds in a day, so that's a good value to use. Click OK and close Regedit. You may have to restart Outlook before it will notice the change. But now the desktop alerts will remain visible for a whole day (or until you click the little X icon at top right).

Calculate more

At first glance the Windows 7 calculator looks just like Vista's version, but explore the Mode menu and you'll see powerful new Statistics and Programmer views. And if you're clueless about bitwise manipulation, then try the Options menu instead.

Click on View and choose different types of calculators that you want to use.

You can calculate your Mortgage, Loan Amount and even Fuel Economy of your car.

 This offers many different unit conversions (length, weight, volume and more), date calculations (how many days between two dates?), and spreadsheet-type templates to help you calculate vehicle mileage, mortgage rates and more.

Don't take any Windows 7 applet at face value, then - there are some very powerful new features hidden in the background. Be sure to explore every option in all Windows applets to ensure you don't miss anything important.