Are you using Windows XP or later? If so, whenever you're connected to the internet, you can "force" a time refresh from the windows time server. Double-click on the clock icon and have a look at the available tabs.
Note this won't work if your system is attached to a domain controller (ie. a work network - I assume not!!!) as it will time sync from the domain servers.
Unless you're never connected to the internet (pretty unlikely), you'll find that the GPS time sync is not as accurate as a an internet based tool like this one:
http://www.thinkman.com/dimension4/
I assume your PC clock is reasonably accurate and doesn't lose time quickly. Just sync before you go out of internet range and you should be good to go.
Sorry this is slightly off-topic to your actual request!
Turbo