Well, simplified, with oem slp activation: Oembios set's CRC must match with string reported by OEMBIOS.exe (if bios is returning a slp string of course) The WINNT.SIF needs a matching key Search OEM.CMD in a txt editor for the CRC of your oembios set and you will find a matching oem slp key Note: a Home key is not eligible to activate Professional and so on SETUPP.INI - must contain "OEM" So, yes, your Dell image will not (and should not) work with HP. Volume activation with a VLK for Professional is less hassle and neutral regarding pc brand, might fit your use better. A XP volume image and a VLK is all you need.