SXS folder in Windows XP

I just notice a SXS folder on my computer and inside it has this security catalog name msxml4.

It provides a mechanism for multiple versions of individual Windows components to be installed and run "side by side."  This helps to address the "DLL hell" problem by allowing an application written and tested with one version of a system component to continue to use that version even if an application that uses a newer version of the same component is installed.

Side by Side (SXS) in XP  can be explained on this page:
http://www.microsoft.com/technet/prodtechnol/winxppro/evaluate/xpprfeat.mspx
 

Further discussion: http://www.experts-exchange.com/Operating_Systems/WinXP/Q_20759045.html

In upgrading an older system from '98 to XP, I encountered the "sxs.dll syntax error on I386/asms/msft/gdiplus.man line 4" error. I tried downloading and replacing the gdiplus.dll file on the target system, but the same error returned. Then I saw builtright's comment about the video card, and replaced the old video with a new XP compatible card, and the problem disappeared with a successful upgrade. I think the real clue was the file name GDIplus.dll