If you learn that a new service pack is available for Vista, but you're worried that your current apps might not work with the service pack, you have some options. Start by changing the Windows Automatic Updates to specify downloading without installing, or to specify notifying without downloading or installing. When prompted for an installation method, choose Custom, uncheck the service pack or patch that you wish to delay or avoid, and then install the rest of the pack. You may be prompted from time to time to download and install the remaining update, but you can decline to do so.

If an update that you have installed proves to be the source of subsequent problems, you can take steps to reverse the damage. If you have Windows System Restore turned on (Start, All Programs, Accessories, System Tools), you can return to a point before the patch was installed, when your system still worked perfectly (note, however, that doing so may also undo any other recent software installations you may have performed).

Another, perhaps easier choice, is to uninstall the patch. Go to Control Panel, Add or Remove Programs. Check the box at the top, if it isn't already marked; the resulting list of installed apps will include Microsoft updates. As you scroll down the list, you'll see a large block of Windows Updates, identified by update number and date. Uninstalling the update with the highest number (or the most recent date) should do the trick. Once the update is gone, Windows will try to reinstall the missing patch the next time it has a chance to--especially if you have Automatic Updates turned on. To prevent this from happening, change your Automatic Update profile (see above) either to notify you of the latest updates, or to download but not install them.

Even if you arrange to delay installing all patches, not every update will go swimmingly. For example, does not install correctly for some people no matter what steps they take to prepare the way for it. The resolution, according to Microsoft, is to remove a particular Registry key, after which the service pack shouldinstall correctly; unfortunately, uncovering that information can sometimes be vexingly difficult. Start by typing the exact error message into Google or another search engine; the results page should include at least one Knowledge Base (KB) article located on the Microsoft Technet or Support Web site.