Disclaimer: Make sure you test this before you go live! Can't be held responsible and all that stuff!

If like me, you like to customise your XP images by integrating tweaked files such as uxtheme.dll, notepad2, etc, you can do this by integrating the files directly into the SP3 file.

If you extract the files using a tool like WinRAR, to a folder "C:\WinXPSP3" for example. You can replace the files directly:

Download the custom uxtheme.dll from here. Run makecab on the file from a command prompt and you should be left with uxtheme.dl_

Do the same for Notepad2. Rename Notepad2.exe to Notepad.exe, run makecab and you should get a notepad.ex_. If you replace these files and then run the \i386\update\update.exe, you'll have a nice customised XP SP3.

One thing to note, you may or may not come across some Windows File Protection issues. If you do, you can disable these as well by extracting the files and following the instructions here

Obviously do test this thoroughly before you do any deployment, but I am running it fine on the machine I have just updated. I will test a few more machines and let you know.

Hope it helps someone at least!