(Updated July 2019) I am posting this message as an alternative to the (not MS Official) WinXP SP4 Update Package. HERE, I kept having stability problems (PC Crashes) after installing the SP4 Package. Which proves NOTHING about whether to use the SP4 Package. MANY others have used the SP4 Package with NO PROBLEM and get a good result. But the SP4 Package is NOT a 'Microsoft Official' Package either.

WinXP_SP3_Updates_Hotfix_List.txt <-- Download (View) this FILE, attached at bottom of THIS MESSAGE here.

https://www.catalog.update.microsoft.com
Download individually KB Updates (Hotfixes) from above (Official Microsoft) URL

As far as SEARCHING for the 'KB UPDATES' -- this seems to have gotten WORSE than it was.
WindowsXP-KB892130-ENU-x86.exe <-- I could NOT get this to LIST at the 'MS Catalog KB UPDATES' site.
But GOOGLE Search = "Windows XP KB892130" did display a URL download (MS Official site).

http://www.catalog.update.microsoft.com <-- Search = "Windows XP"
It lists categories like "Critical Updates" , "Updates" , "Service Packs" , etc.
Mostly, using say Search = "KB946648" will list the item for download -- but NOT always.
Best of luck on the Searching, you may be better at it than me.

So first, install (re-install) the WinXP SP3 (Service Package 3).
Hopefully then, WinXP is rebooting and stable for you.

Then you can MANUALLY install the UPDATES to WinXP SP3 (Hotfixes) via using the FILE LIST (attached here).
Download and Install the KB FILES (*.EXE) from the 'MS UPDATE CATALOG' website.

So, you just 'grind through' installing the LONG list of KB UPDATES for WinXP in a 'one at a time' basis.
This is TIME CONSUMING but simple, and you can eventually get it done.

http://icrontic.com/article/repair_windows_xp
Finally, IF you continue to have PROBLEMS with WinXP, consider to use the SYSTEM REPAIR feature via RECOVERY CONSOLE of WinXP (using the official WinXP Install CD, boot up with that). THAT should definitely get you back to a STABLE WinXP situation. This should give you a CLEAN REGISTRY type situation with WinXP. THEN, you can install SP3 (Service Package 3). And THEN, you can install the KB UPDATES as described.

Hopefully, you get most all of the 'critical' KB UPDATES for WinXP SP3 installed properly.
This is more a 'minimum reasonable' suggestion for WinXP SP3 and KB UPDATES.
IF the WinXP SP4 Package works for you, that might well be a better choice.

WinXP OS is NOT supported officially anymore. However, there are BROWSERS that support WinXP.
(NEW MOON Browser = 'Pale Moon' fork by @roytam1) is updated to work with websites via WinXP.
NEW MOON (and Other) Browser for WinXP usage by RT (Click for FORUM Support Thread MSFN)

WinXP_SP3_Updates_Hotfix_List.txt

Edited July 5, 20197 yr by TechnoRelic

Still on the fence, whether or not to go with SP4; I might still.

Would be worth taking the time to manually install each update while we can.

Thanks for the advice here!!