Slipstreaming XP SP3
Step 1 - Install nLite
Step 2 - Copy the XP source files from an XP CD
Step 3 - Fire up nLite
Step 4 - Select the source files
Step 5 - Well, there is no step 5
Step 6 - Select the nLite options
Step 7 - Select the service pack source files
Step 7 - All the heavy lifting is handled for you
Step 7 - Done
Step 8 - Creating the ISO file
Step 8 - It only takes a few seconds ...
Step 8 - Done!
And that's all there is to it!