[UK-CONTEST] Methods of updating the PC clock?

[G3UUT]

The recent debate about contest start and finish times and a wish to 
improve my shack technology (from using the speaking clock) has prompted 
me to ask the following;

1. Somebody mentioned using internet time servers.  I've never been able 
to get these to work.  Is there a simple and foolproof way of doing it 
from the UK? (I'm not very PC literate).

2.  I've seen these surplus Trimble GPS frequency standards available on 
the internet which look an ideal way of getting a good frequency 
standard for Test equipment and transceivers - especially on 
VHF/microwave both at home and /P.

http://cgi.ebay.co.uk/Thunderbolt-PRECISION-GPS-10Mhz-1PPS-Standard-Easy-Kit-/290322053618?pt=LH_DefaultDomain_0&hash=item43988af9f2

http://cgi.ebay.co.uk/Thunderbolt-PRECISION-GPS-10Mhz-1PPS-Standard-Easy-Kit-/180419218430?pt=LH_DefaultDomain_0&hash=item2a01d2cbfe

Does anybody know of a relatively simple software/hardware way of also 
using the GPS time output, which they presumably must also have 
available, to lock up the PC clock?

Thanks
John G3UUT