HP noted that it will support downgrades on its business-class PCs, implying that it will provide drivers for those machines.
Although HP's for-consumers PCs come standard with Windows 8, customers who have factory-upgraded to Windows 8 Pro -- an option available on many machines -- acquire downgrade rights.
In general, it's a better idea to stick with Windows 7 if you can until the software development community can fully adopt to Windows 8. Add to the fact that Windows 7 already has it's first service pack out and that makes it a more stable option, and that a lot of users have had poor reactions to the 8 interface so far.