Time Sync NetTime NTP Time Client
NetTime Software does not produce time synchronisation software that synchronises your PC clock with a time server. There is another product called NetTime that is available free of charge.
Here is the web address: http://nettime.sourceforge.net/
Alternatively there are a number of commercial grade NTP time clients and time servers. A simple Google search should provide you with a number of options to look at.
If you are looking to synchronise your Windows XP Clock, you may be pleased to know that you have built in NTP facilities. In addition to this, Microsoft provide a free time server to which you can synchronise your system clock.
Windows 2000 also provides built in time synchronisation facilities but they are more complicated to set up. Please refer to Microsoft documentation: http://support.microsoft.com/kb/q216734/
Microsoft's free to use Time Server: time.windows.com
Please note: Do not enter this into a web browser, it is an NTP server and should only be used for Time Clients