Not a dangerous problem to worry about.
That's the update to the Microsoft Malicious Software Removal tool.
You received it as part of a Microsoft update.
Microsoft automatically creates "backup" files for MS Updates when the file already exists, but is being replaced by an updated version. That way if the new update causes problems on a user's computer, it can be removed and replaced from the backup.
Since you already had a version of Microsoft Malicious Software Removal (all XP users have it), the November update created this backup and log file.
If your machine continues working as normal, you can delete these two files…….. but you will not be able to replace the update with the older version if "for some unknown reason" you decide you want to do so.
Essentially, these files "appear" because during the update, Microsoft installer didn't clean up after itself and left the "temporary files" it created during the update.
You can find a handy little utility by DougKnox, that cleans up after such circumstances.
Caution: using the tool does prevent any future attempt to reverse the MS update.
http://www.dougknox.com/xp/utils/xp_hotfix_backup.htm
Most "newer" XP users would just leave both, even though they are a temporary clutter of junk files.
If you feel comfortable, that you are a more experienced user and understand what happened here. (from my explanation, or from the DougKnox link, then go ahead and use the tool or delete the files manually.
If not leave them there. No harm - No Foul. Just a bit of clutter.
The "slow-down" that you think you might have experienced, is most probably unrelated.
Have you Defragged you Hard Drives recently?
Now would be a good time.
Best Regards
