Windows does not display the seconds you need a third party program installed if you require this.
HOW TO: Change Date, Time, Number, and Currency Value Displays in Windows XP
To Change the Time Display
1. In the Customize Regional Options dialog box, click the Time tab to specify any changes you want to make.
NOTE: To configure the settings so that the leading zeros in single-digit hours, minutes, or seconds are not displayed, type a single uppercase H, or lowercase letters, such as h, m, or s.
2. If you do not see the format you want in the Time format box, use the following guidelines:• To display time in a 24-hour format, type an uppercase H or HH for the hour.
• To display time in a 12-hour format, type lowercase h or hh for the hour.
• To display leading zeros in single-digit hours, type HH or hh.
• To display a single letter to indicate AM or PM, type lowercase t.
• To display two letters to indicate AM or PM, type lowercase tt.
• To display text, type single quotation marks (') around text.