A simple but useful option available in Windows 7, which many may not be aware of, is the ability to display up to 2 additional time zones via the System Tray Clock. Living in Oz and continually battling the time differences, I have found this to be particularly helpful.
Left click on the time display in the System Tray and select “Change date and time settings”. Now click on the tab for Additional Clocks. Place a checkmark in the little box next to “Show this clock” and then select the appropriate time zone. Give the clock a suitable name and when all finished just click Apply:
Now, hover the mouse cursor over the time display in the system tray to reveal times in an abbreviated textual format:
Or, left click on the time display to reveal times in full graphical view: