We can add two additional clocks of different time zones in windows 8 as well as in windows 7. The procedure is quite simple.
Click on the date in the desktop corner
Click on time and date settings
Click on additional clocks
Add two additional clocks of time zones you wish to. and give appropriate name also. Don't forget to check show the clock box
Your clocks are set. Now you have two additional clocks
If you want to disable the Clocks you just go to the previous window as shown below and uncheck the Show the clock box