HP laser on network

We are adding two HP laserjet printers to PCs on a peer to peer network. I am running Dave2.01 software and have no problem addressing a existing printer connected to one PC already except that it doesn't do postscript. now that we are going to add a III and a IIID It would be worth my while to investigate postscript support for these printers. Does anyone know what Cards/part#'s need to be added to these machines for it to be postscript compatable?. I am not connecting to these machines directly from the Mac or through Appletalk but through Dave2.0, to ethernet, to Windows NT, on a PC, through its port, to the printer. I do this now but get garbled text printed out because the printer does not have postscript.
Thank you
Greg Vincent