The issue is not HP's alone, no vendor supports their equipment indefinitely. Obviously if it's using a parallel port, it's getting rather old and from HP's statement that they don't support it with Vista drivers, that means they've dropped that model from the active support list some time ago.
All vendors are the same, Epson, Canon..etc, they all discontinue support on aging equipment after some time, so no matter who you buy from it will eventually be the same thing. If a newer HP printer has what you want in a price range you want, over another brand, don't let the fact that they discontinued supporting your old printer deter you from looking at it, whatever you buy that's going to happen sooner or later.
XP drivers will never work with Vista or Windows 7 as the core systems are just too different.