My first thoughts on Microsoft Windows Service Pack 3 are: its shit!
I was reading around and saw that Service Pack 3 supposedly speeds up folder load times. I have a folder which includes several thousand MP3s and the amount of time it takes to open the folder so that I can navigate through the folder is the same prior to installing SP3.
Besides that, it patches the UXTHEME.dll file. The UXTHEME.dll file is a file that allows you to utilize un-signed themes. These themes are customized and built by others who do not work for Microsoft or have an affiliation with Microsoft.
I have SP3 installed on a test bench but went ahead with the installation of SP3 on my main bench. The reason was related to testing it out on my test bench. Everything seemed fine, except for the two minor things I’ve already mentioned.
It will be nice to have the entire updates since SP2 into one big SP once the service pack is finalized. Until then, I would recommend staying away from Windows XP Service Pack 3.