Similar situation to others, in that I have an HP machine that has a CoA for Vista Home Premium on the side but I don't have the installation media. Old HDD died and with it the restore partition and my mum (her PC) never made the restore disks. I have a Dell Vista Home Premium disc that I have made an .iso from (MagicISO), have tried to understand how to create an HP disk from the Dell one but the guide assumes a bit too much knowledge in this area for me. Am happy to type in the key when installing it and validate online or by phone (it is a genuine key on the oringal CoA on the case, so I don't see any issues), so do I need to worry about adding an 'SLP' key to the image, SLIC tables etc?
Just use the dell dvd and install vista once installed use Daz loader it will install your HP certificate and key. P.S. the loader itself will not be installed because you have SLIC 2.1 in bios.