It can wreak havoc at home too, for instance with my PVR server. Wrong time means wrong recordings. On top of the Windows issues, Java (what SageTV is written in) has its own bloody time and you need to update that separately on top of the updates for Windows.

The new US DST rules took effect in 2007 and had been planned for a long time before that. Plenty of time for anyone to make a dozen updates ahead of schedule. MS has had to issue time zone hotfixes every year since then, which also include changes to other countries of course. Even when you sync with a time-server, if your tables are off, you won't get the correct time. Yesterday, before the latest update, I was off by 2 hours after a sync.

Speaking of sync, does Windows 7 always work with ntp? I had to do a song and dance ad some registry fiddling to make sure XP would properly hit the nntp server for updates. And then I had to use Apple's server to get accurate time.