Another way which I did on my Dell XPS 15 in Sep 2011. Delete all partitions, and install windows 7 ultimate. I have an Ultimate key from Technet but one can also activate safely with Daz loader found on this forum.
Actually I always follow acyuta's procedure But as he want to update from Home Premium, so I told him that way
Since the original licence is not to be used, that is why I suggested this method. Just get the drivers for the specific laptop. Further, since generally preinstalled OEM laptops usually have office 2010 starter, even that can be junked. Of course, if this seems a hassle, then the solution in post 2. However OEM laptops are usually loaded with crap which should be rid off. Further, the system recovery image also becomes outdated pretty soon. Best method is clean everything on hard disk, install windows 7 ultimate, activate with daz, install other software, and then make a system image with Acronis. Even Acronis is free if the hard disk is from WD or Seagate. Just go to the hard disk manufacturer site and download.
@ Tito and acyuta In short word, It is better for me to re-install Windows with fresh Ultimate Edition and then install CERT and OEM SLP Key ( HP Ultimate Key ), Is that all what you mean ? Thanks for your concern.
You can use the method in post 2, but in a fresh install of windows 7 ultimate, just download the Daz Loader from this forum. Then click and activate. No other stuff required. Get the drivers for your laptop from HP site. However, beware that laptop drivers are a bit tricky in the sense that some install order has to be maintained which I learnt from 2-3 reinstalls. However that was worth it and I have a laptop just the way I want it, with the software I need, and with an Acronis image for the system. In my Dell XPS15, I usually start with all Intel drivers (chipset, RST, MEI, graphics). Then Renesas USB 3.0, STMicro motion sensor, bluetooth/wifi drivers, then nvidia and all the others. Around 50-60% of the drivers on the website are useless. To know what is installed on your system including drivers, just go to control panel-programs and features. That will give you a very good idea of the software and drivers that were preinstalled by the OEM manufacturer prior to shipment. In my case, I install only those drivers and in six months have not faced a problem. Just that I use graphics drivers from Intel and Nvidia rather than from Dell (which are usually older).
What version should I pick in the downgrader utility to go from Home Premium to Professional? I only see the Install option when I launch setup.exe (tried with retail Pro and OEM Ultimate media), at which step is there the "upgrade" option?
Quite simply - you can't... Professional is better than Home Premium so DOWNGRADING can't work - HOWEVER, you can run "Anytime Upgrade" and enter a valid key if you want to UPGRADE. Also note that in both cases it is x86->x86/x64->x64 ... not ... x86->x64/x64->x86 since those instead require a fresh reinstall