When you try to build a slipstream from a distribution share, you receive:
Not all files necessary to perform an integrated installation are present.
This issue will occur if you only copy the i386 folder to the distribution share.
You MUST copy the entire contents of the product CD-ROM to the distribution share.
When you download the Service Pack exe file, you must expand the Service pack using:
<Service Pack File Name>.exe /x
To build the slipstream:
<Expanded Service Pack Path>\i386\update\update.exe /s:<Path of Distribution Share>