Install the system from a standard windows cd/DVD that matches the license on the bottom of your laptop.
If it is win 7 you most likely will not even need drivers.
If you do you can get them form HP's website.
That's the way I would go too, it's probably Win 7 64bit, but may not be so easy to get an installation disk. At least if HP would send out a Recovery disk it would all be together. As you say, most of the drivers will be found by Win 7...