I hooked up a HP 4180 Photosmart printer-copier to

When you say "the scanner works" do you mean you can make a photocopy OR you can scan a file into the computer? Many people think scanning means copying. They are not the same. If you can scan a file into the computer then your connections are sound and the problem lies with the printer driver side of things
Normally this is the procedure on a mac:- go to the printer set-up panel in System preferences. If the printer is listed, highlight it and then delete it.
Click on the plus symbol to add a printer. If the computer can see the printer it will automatically add it to the list. If the correct driver is available it will load by itself.
See if you can print now. NOTE: we have not used any CDs yet. My experience with HPs is that generally the software on the CD is not up to date and that supplied in the Mac is generally more up to date.
If it still doesn't work then go to the HP website and download the latest driver you can find and install it. Then go through the routine above once again.

uninstall...reinstall and make sure you are using the mac drivers.