this is common and not just with HP ,you will be hard pressed to find a printer manufacturer who will continue support for a printer more tnan 3yrs old sometimes less, I have gotten around this several times by using compatability mode .
you say you cannot get it to even try Vista drivers ,strange as most vista drivers work in win 7 . do you install in compatability mode ,or do you try to install first and then run in compatability mode, if you place the vista driver on the desktop and right click/properties/compatability , tick the (run in compatability mode etc.) box and select the correct version (ie.Vista) for the driver ,then OK and apply . then install ,it should install in this mode.
you could Dual boot , XP--Win7 ,this will allow you to use all your favorite softwares ,new an old.
this scenario is one of the many reasons I use HyperOS to multi boot ,I simply dont get those types of problem anymore ,however that aside ,you should definately be able to at least install and run it in compatability mode .