Yes, try the following
People who use Windows may have
noticed that the clock in the system
tray displays time in the 24 hour
format by default. I always prefer 12
hour format, if you want to know how
to change it or if you simply want to
get rid of AM and PM to save the space
to stick in one more taskbar icon!
Well, here is the solution.
In order to change how the time is
displayed on your computer, click on
Start > Control Panel, and choose
Regional and Language Options.

Click the Customize button underneath
the Standards and formats section.
Below that button, you’ll also see an
example of how each setting is
currently configured for Number,
Currency, Time, Short Date, and Long
Date.

Click on the Time tab and change the
time format to H:mm:ss (note the
uppercase H) and press OK

The uppercase H or HH stands for 24-hour format, whereas the lower case
h andhh means 12-hour format. The
single h is if you do not want to
display leading zeros for single digit
hours and hh is if you want a leading
zero.
To further customize your Date / Time
settings, here are some useful tips:
- Type uppercase H or HH to Display time in a 24-hour format
- Type lowercase h or hh to Display time in a 12-hour format
- Type two characters, HH or hh to Display leading zeros in single-digit
hours
- Type a single uppercase H, or lowercase letter, such as h, m, or s
to suppress the display of leading
zeros in single-digit hours, minutes,
or seconds
- Type lowercase t to display a single letter to indicate AM or PM
- Type lowercase tt to display two letters to indicate AM or PM
- Type single quotation marks (’) around text to display text