ArcPress does not autoselect any ArcPress driver when printing to an HP DesignJet 4500.
The ArcPress properties dialog box may display the message: "No default driver match found. Please select the driver that you would like to use." If the ArcPress HP Universal driver is selected, it may display the message: "The ArcPress HP Universal driver does not support the currently selected printer model: HP Designjet 4500ps HP-GL/2."
This a known issue.
A new HPGL driver for the DesignJet 4500 became available in July 2006. This driver version, 6.17, reports a model name string that is different than the string for the prior versions of the DesignJet 4500 driver. This model name is not properly recognized by the ArcPress HP Universal Driver and is not properly autoselected when printing with ArcPress.