We're mere days away from the government's oh-so-wise-let's-do-it-three-weeks-early switch to Daylight Saving Time, and if you haven't heard yet, it's causing havoc with various computer systems, mobile phones, and calendar entries that people created months ago and only now are starting to realize that they may soon be incorrect when DST hits.

On your PC, adjusting for Daylight Saving (or Savings) Time means more than just tweaking your clock ahead an hour. The problem is with third-party applications and with devices that you attach to your PC and which sync with it. If one of your programs or devices doesn't know about the early switch to DST, that could throw a major wrench into things when you try to synchronize data. At worst you might be an hour late for a meeting or two over the next three weeks, but there's no reason to subject yourself to such a headache. Patch your gear now and avoid frustration come March 12.

Here's what to do, broken down by gadget.

Windows PCs. If you're running Windows XP or Vista, running the regular Windows Update patches will ensure your system is up to speed.  But you'll also need patches for Outlook, if you use the program. The best place to start is Windows' DST center. Just click the link and step through the options, indicating which OS and Outlook version you use. If you have an older version of Windows (2000, 98, 95, or NT), I have a post here on patching your older PC for DST. You'll also have to patch Outlook separately. Here's the download and instructions for doing that.

Macintosh Computers. You may need more than one patch to handle DST, depending on which apps you run, but start with patching OS X to at least 10.4.8. Other updates (you will have to search for "Daylight Saving Time" to find them all) are available for earlier OSes and other programs. All patches are here. (As of November 2007, most Macs should be fully patched.)

Smart Phones. This is the real trouble, where most of the headaches will arise for people due to the aforementioned out-of-sync issues. For best results, patch your smart phone immediately after patching your computer. Still, I've read reports that even with a patch, some appointments made in the past may not be properly timed, so spot-check your phone's calendar after you run the patch to see if appointments are correct. Remember also that if you use push email from your company, it's critical that it patches the email server as well. Bug your IT guy and make sure this has been done, which any decent-sized IT department will have already completed. Here are links for the most important devices: RIM BlackBerry, Palm Treo, Windows Mobile devices.

Everything Else. TiVos have already been patched via an automatic download. Sunbird is patched in the latest release. I can't think of any other devices or programs that might require special patching (most will simply sync with your PC or via the network), but if you have an obscure calendar or PDA, try searching for the model name plus "DST," and you should turn up any available patches. Note that older gear that is no longer supported will probably not have a patch available, so you may have to set the clock forward manually this weekend then adjust accordingly in the first week of April. Don't panic.