Vista makes it very easy to add a network printer. A friend bought an HP laptop and wanted it set up on her LAN to print to a HP LaserJet 5N printer attached to her desktop. So I went into Visa's 'Add Printer' wizard on the laptop and it discovered the shared printer on the LAN, installed it and said it was installing the driver by querying the printer. So far, so good. But printing always caused the LaserJet to hang with a "Processing Job" message displayed on its LED screen. Only a power cycle on the printer would clear this.
I tried visiting the HP site, and found this page http://www.hp.com/cpso-support-new/SDD/main.htm?cc=us&lang=en which claims to install an ActiveX control that will detect whether the correct driver is installed. I suspected a driver problem, so that seemed just the ticket. It installed and claimed the wrong driver was installed and that it fixed it. I rebooted, reprinted - and no cigar - still "Processing Job".
I thought maybe the HP site hadn't installed the right driver after all. Going back to the HP site, and searching manually for the Vista driver for the (discontinued) LaserJet 5N, I found a page that claimed the correct driver ships with Vista and there is no download available. Hmm...
I went to the Printers control panel, right clicked on the printer and selected "Properties" from the "Adminisrator" submenu in the context menu. This showed me that in fact the HP LaserJet 6N driver was installed - not the 5N. Ah ha! So I clicked the "New Driver" button, navigated the control that came up with printer manufacturers listed on the left and model on the right - found the "LaserJet 5N" driver and installed that. Rebooted. And it worked!
So the advice - don't believe either HP or Vista if they claim to have found and installed the correct driver. It's like the old journalistic saw: "If your mother says she loves you - check it out." The devil is (usually) in the details - in this case, the difference between a 5N and a 6N. :)