It is possible to display the version of Windows in the lower right corner of your desktop. This requires a modification in the Windows Registry.
You cannot decide what text you want to appear; it's predefined, based on the version of Windows you are running. For example, the text for Windows XP Professional with Service Pack 2 will be along the lines of:
Windows XP Professional
Build 2600.xpsp_sp2_rtm.040803-2158 (Service Pack 2)
1) Click the Start button, click Run, type regedit and click OK
2) On the left-hand side, navigate to (and highlight)
3) On the right-hand side, locate PaintDesktopVersion and double-click it
4) In the pop-up window, change the data to 1 and click OK
0 = Hide Windows version from desktop
1 = Show Windows version on desktop
5) Close the Windows Registry Editor as well as your other programs and reboot (or log off and log back in).
Originally submitted by Sean.