During using Debian Etch I found some issues which I have described in this article.
Ugly fonts in the Iceweasel (Firefox) application
When I changed Gnome to KDE the fonts in Iceweasel became to differ from other GTK applications (e.g. GIMP, Evolution). For resolving this issue I found the following solution:
Add this string
gtk-font-name="Your favorite font name and size" in the gtk config. In my case this look like this:
File “.gtkrc-2.0.mine” included in the .gtkrc-2.0 :