I know that Quanta is in the Debian and Ubuntu repos and can be installed without doing a full KDE installation. It may also be available through the Mandriva/Red Hat ones--I don't have a Red Hat-based machine so can't test that with the installer.
You shouldn't have to install KDE instead of Gnome; you can install it along with Gnome.
They can coexist as desktop environments without problems and you should be able to switch between them at log in.
I have both KDE and Gnome installed on my primary laptop for the libraries (and I use Fluxbox for my desktop, go figure).
Personally, I prefer
Kompozer, which is a fork of the now-inactive NVU project.
