Here's my old NTP synchronising registry snippet.
Cut and paste this into notepad and save it with a .reg extension (not .reg.txt). If you do it right you'll see the icon change to what looks like a blue rubik's cube. Double-click it and choose to merge it into the registry, and next time you reboot (or restart the windows time service) you'll get time synched to GMT.
Code:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config]
"MaxNegPhaseCorrection"=dword:00001c20
"MaxPosPhaseCorrection"=dword:00001c20
"AnnounceFlags"=dword:00000005
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters]
"NtpServer"="0.uk.pool.ntp.org,0x1 1.uk.pool.ntp.org,0x1 2.uk.pool.ntp.org,0x1"
"Type"="NTP"
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient]
"SpecialPollInterval"=dword:00000384
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer]
"Enabled"=dword:00000001