As we all know Microsoft has released the final version of Windows XP SP3 to public and its available via Automatic Updates, Windows Updates and Downloads Center.
Earlier we posted about it at following link:
Windows XP SP3 RTM Available on Windows Update, Automatic Update and Download Center
You can download the SP3 from the above mentioned link.

I have received a few mails mentioning a strange problem which occurs while installing SP3 in Windows XP. A few people told me that whenever they try to install SP3 in Windows XP, Windows shows following error message:
Service pack 3 setup cannot update a checked (debug) system with a free (retail) version of service pack 3, or vice versa.

The reason behind this problem is that the update package installs retail bits on retail builds and checked bits on checked builds. But you can spoof Windows updates in order to install retail bits on checked builds and vice versa.
If you are also facing the same problem, then follow these simple steps and your problem should be solved:
1. Type regedit in RUN dialog box and press Enter. Now goto:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion
2. In right-side pane look for a String value "CurrentType". Change its value to Checked and if its already set to Checked, then set it to Free and click on OK.
3. Exit registry editor and try to install SP3 again. Now it should install without any problem.
This article was posted by VG in following section: Troubleshooting, Windows XP.
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Aditya
thnx a million Ernie..
macs
thanks. it worked
emerton
you rock vishal
topguy
thanx for the solution, it worked!
anywayz, facing another problem, it said i can't install sp3 on top of my older sp3
VG
^^ Thats true. You'll have to uninstall previous SP3 Beta or RC before installing this new final version.
Ryan
Mine said "Multiprocessor Free" so I changed it to "Checked" and it worked like a charm. Thanks!
VG
^^ Glad to know it worked for you. :)
VARUN
I install sp3 a few days before after full installation it forms a loop
it restart> boot up > restart >..............................
what's that mystery ..............?????
vg do u have any solution
another dude named lucas above in forum have same problem
> i have dwnld > it pro pack
> changed from Multiprocessor Free to checked >...................!!!!
VG
^^ Some motherboard do have problems with SP3 which ends in restarting loop. Try to slipstream SP3 in XP setup and then reinstall it.
Klavciceva republika
Thanks a lot it works: