Whats this "XML Parser 3.0" for?

Anyways when Installing I had the following message pop up a number of times.

"Files that are required for windows to run properly have been replaced by unrecognized versions. To maintain system stability windows must restore the original versions of these files. Insert XP pro now"

It never specifies which files.(kind of annoying to be asked if I want to replace unnamed files) Some of these files may have been replaced by XP antispy as a way to disable XP pros more annoying automatic features. Anyways I lost my XP pro CD when I moved last fall.

In any event installing msxml3usa.msi did not fix the problem. I still can not load the windows update webpage.