Here's a list of all HP Designjets -- click on the name of your Designjet and see if a driver is showing. Note: Usually you can use any driver from your series. Just be sure to use a 32 bit driver if your computer operating system is 32 bit and a 64 bit driver if your computer has a 64 bit operating system.
You can also find the HP.com Wide Format Printing Forum HERE. A very helpful resource!