The large Home Design software download...
...should be available as a CD. If so, get it.
Be sure their software is correct for the
computer version you have. If you have a
PPC Mac, and the software is for an Intel
Mac, then you may have some issues.
The HP web site has their latest drivers for
all in one print/scan/fax/copy devices. I have
one and got a suitable driver from them direct.
And it was free. (GutenPrint is another option.)
There is some info in a second link in this page;
in addition to a driver you may or not need:
http://www.apple.com/support/downloads/hpprinterdriver11.html
The external enclosed hard disk drive should not
require extra software to use it with a Mac. If it
did require reformatting, for a specific purpose
for use with a Mac, and you desired it so, the
Disk Utility in applications> utilities folder could
be used to reformat to HFS+.
•The computer's OS may have been trying to
Index the external computer. You should be
able to have the Mac OS X ignore that drive.
{Have you tried using the bootable installer's
version of Disk Utility to 'repair disk' and also
to 'repair disk permissions' on the Mac's HDD?
I rarely do that; but do start in SafeBoot and
then repair disk permissions, then restart.}
If basic maintenance has not been done, to
repair permissions is an early first step; and
the computer's own DU is a thing to use for
repairing permissions before and after installs.
There may be some other issue behind the
set of symptoms you have noticed. These
would require more information in order to
proceed.
Is the printer using Ethernet or USB to connect
to the computer? Is the external drive a USB or
is it a FireWire enclosed drive? What was its
purpose in the configuration you are setting up?
And, which iMac do you have? If it is an iMac G4,
then you are in the correct forum area. The name
of each section is above the topics with it; and it
also is a hot link to a main list of each iMac area.
Good luck & happy computing! 🙂
edited to add driver info link.