Anyone know a work around for installing new OS to a new Hard drive in this old laptop, cannot be installed from cd drive or usb as is designed for network install only.
I think you may find a boot option (Multiboot?) in BIOS setup - with the correct setting you may be able to autoboot your CD drive and install the OS to your HDD.
Have only a little experience of this system but surprised that no bios options so, being curious just checked the HP site and found this for the HP Compaq Business Notebook nc4000 Series: A bootable medium or network interface card (NIC) contains files needed by the notebook to start up and operate properly. The MultiBoot utility, disabled by default, enables the identification of devices, and control of the sequence in which the system will attempt to boot those devices, to start up the notebook.
Bootable devices include optical drive discs such as CDs or DVDs; bootable diskettes and SuperDisks; or a network interface card (NIC).
NOTE: Some devices, including USB devices and the network interface card (NIC), must be enabled in Computer Setup before they can be included in the boot sequence.
Full details Clicky
I hope that you may be lucky and find the options are there but hidden!