One more reason not to install XP Service Pack 3, or if you’ve already installed it to remove it…
XP Service Pack 3 blocks .NET security patches
By Susan Bradley
Installing SP3 on Windows XP eliminates the operating system’s ability to install important security patches for Microsoft’s .NET technology and possibly other software.
This problem forces XP SP3 users to apply patches manually to complete vital updates.
The new error is the latest in a long series of glitches relating to XP’s SP3, which Scott Dunn described in his Sept. 11 Top Story. The issues include spontaneous rebooting of systems based on AMD chipsets, as documented by Jesper Johansson in a blog post from last May.
To determine whether your XP SP3 system has a version — or multiple versions — of the .NET Framework installed, open Control Panel’s Add or Remove Programs applet and look for it among the list of currently installed programs. If you don’t see any .NET entries, you don’t have the framework installed on your system and needn’t be concerned about the update problem.
If you do see a listing for Microsoft .NET Framework, you need to use a third-party update service such as Secunia’s Software Inspector (described below) to patch the program.
To read the entire article, click here – http://windowssecrets.com/2008/12/04/03-XP-Service-Pack-3-blocks-.NET-security-patches/?n=story1