Go to the HP Support site and enter your exact laptop. You might be able to simply type in your laptop code, I'm not familiar with their procedure.
When you find the exact site for your laptop make sure to use the proper Windows 7 drivers whether 32-bit or 64-bit.
You generally HAVE to use the correct drivers.
Having said that:
Are you saying that you are installing Windows 7 Ultimate yourself AND that Windows 7 support is not available from HP for your laptop?
If so, you should try the Vista drivers instead.
If your really stuck then you can go to the video card manufacturer directly Intel, AMD, or NVidia and look for the mobile drivers.
As for audio, if you can't update as I said, you need to find out which chip you have (i.e. Realtek 889) and get those exact drivers from Realtek for your version of Windows.
Windows may add generic drivers but these may not be optimal.
Some functionality on your laptop may be missing if you haven't installed certain software or drivers.