Try it in safe mode with all AV & Firewalls disabled.
Then if that doesn't help google "Security Update for Windows XP (KB828741) unsuccessfully updated" and check out the options.
BTW How can something unsuccessfully update?
MartyMcFly
Practically a Master Poster
678 posts since Feb 2005
Reputation Points: 16
Solved Threads: 17
Try downloading and installing it again. It has only been unsuccessful because the download itself has failed or been corrupted in transfer.
Catweazle
Grandad
4,335 posts since Mar 2004
Reputation Points: 229
Solved Threads: 149