I've been trying to get Vista to update its time from an internet time server and it just won't work. I've tried different time servers, including ones not on the default list, disabling the Windows Firewall and stopping/starting the Windows time service.
When I click the "Update now" button, it waits for about 10 seconds and then says there was an error updating the time. No description of what the error is, just that there was an error. I used Wireshark to check whether Windows was sending anything out over the network when I clicked Update Now and no, it does absolutely nothing, even with the firewall disabled.
I'm now using About Time 4.8 to update the time from pool.ntp.org
About Time is quite old software, since XP came out, this sort of program isn't much use to most people. It was no used to me either until I started using WSPR and need a clock which is accurate to within a second.
XP updates its time with no problems on the same computer.