With Windows XP you can easily synchronize computer time with internet. If your computer is a member of a domain, you shouldn't have to worry about time synchronization. Probably it synchronizes with a network time server.
If you use your computer at home, there is a good chance that it isn't member of a domain. Even for home and entertainment use, your computer clock should be running accurately. You can set it up so that it always shows the right time.
There are internet time servers that you can use on the internet. If you set up your computer to synchronize with one of those, your computer clock should be fairly accurate.
Double-click the clock in the right-hand corner at the bottom of your screen.
Windows shows the date and time properties dialog
Click the "Internet Time" tab (this tab isn't available if your computer is a member of a domain)
Check the "Automatically synchronize with an Internet time server" checkbox
To test if the connection with the time server, click the "Update Now" button
If the synchronization works, you should see a message that the time synchronization was successful.
If the synchronization doesn't work, you can try the server drop-down list to select another time server.
You will also see the date and time of next synchronization in this dialog. Normally your computer synchronizes with the time server once a week. It's really that simple to synchronize computer time with internet.
If synchronization with the time server fails, it could be for one of the following reasons :