Not necessarily anything wrong with the board, the POST screen is hidden on a lot of PCs. Try just hitting F8/F12/DEL as it boots up, see if it allows you to access anything.
By "no hard drive" I'm assuming you mean it says there's no boot device?
Ways to ensure the HD is being recognized by the motherboard:
BIOS, should show up under "advanced" settings or the like... as an IDE device
Many PCS display a list of attached hardware between POST and boot, but it won't stay up long and may be hidden by the HP logo.
Boot to a CD or flash drive, and attempt to access the drive from there.
http://gparted.sourceforge.net/livecd.php
Gparted liveCD is a great bootable partitioning utility. I use it a lot at work. If the hard drive is detected, you should be able to boot to the CD and use it to reformat the drive (probably want to format it as one large NTFS partition).
If the hard drive isn't being recognized by the motherboard, make sure that it's connected. You said it's old, so it is probably IDE. It should have a power cable connected to it, from the power supply (4 pin, multi-color wires). As well as a wide, flat IDE cable connecting it to the motherboard.
If it's physically connected but not being detected, ensure that the jumpers on the drive are properly set. If it's connected and set up properly, it might just be dead. Strange noises or no vibration/noise at all is a good indicator of a dead drive.
I know it's a lot of stuff to digest, I would start by making sure it's physically connected... then try the boot CD.
lemme know how it goes