If you reinstall Windows XP, you normally have to reactivate it, but there's a way around reactivation. Windows XP maintains the activation information in the file Wpa.dbl, which you'll find in the Windows\System32 folder. After you activate, and any time you add hardware to your system, back up the file to another disk. If you need to reinstall Windows XP for any reason, go through the installation routine, then copy the latest version of Wpa.dbl to the Windows\system32 folder.
When you're troubleshooting a problem, it helps to reboot without launching the items in the Startup folder. In some cases, the problem may go away, which indicates that the problem is a conflict with one of those applications. In cases where these items have no effect on the problem, skipping the Startup folder may still speed up the reboot considerably, which is convenient if you have to restart repeatedly. To skip loading the items in the Startup folder, hold the Shift key down during boot-up.
You can update Windows XP manually by choosing Start | All Programs | Windows Update. In Windows 98, Me, and 2000, this option is listed at the top of the Start menu.
Windows XP and 2000 offer an Automatic Updates feature to ensure that you always have the latest Windows fixes. In Windows XP, you can turn Automatic Updates on from the System Properties dialog box. Open the Control Panel and choose System. Next, choose the Automatic Updates tab; turn the feature on, if necessary, by clicking the check box Keep my computer up to date at the top, then choose one of the options for how you want updates to be handled. For Windows 2000, you set options by going to Control Panel | Automatic Updates.
If you want a lot of control over what's being installed (or don't want to be a guinea pig for brand-new updates), choose the option to have the system notify you before downloading updates and again before installing them. This lets you review what updates are available and decide whether to download and install them on a case-by-case basis. But remember, it's a good idea to install security updates as soon as they are available.
Sometimes, when you uninstall a program, its entry remains in the Add/remove programs listing. Or you might delete something manually and find that the entry remains in the list of uninstallable programs. You can clean up the list and remove programs that you've already uninstalled. Run Regedit and navigate to:
HKEY_LOCAL_MACHINE\ SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
From there, you can remove any unwanted items, which are in the form of Registry keys.
A file association specifies which application is the default for a particular file type. When you open a file�an MP3, for example�the associated program launches. To change the current file association for a file type, or to create an association, right-click on a file with the appropriate extension, and select Open with. (In Windows 98, you need to hold down the Shift key when right-clicking.)
In Windows 98, Me, or 2000, select the program you want to use from the list that appears, or Browse for another application. Windows XP will show you a short list of recommended programs or let you Choose Program. Check the box labeled Always use the selected program to open this kind of file, and choose OK.
If you're using Win XP and not sure which program to use, and you are connected to the Internet, click on the link called Look for the appropriate program on the Web to go to a Web page that may help you find out the correct program to use.