The fonts used in konqueror file manager (and elsewhere) are at 1024x768 resolution are barely readable and little improved at 800x600. I refer to the drop down menus and the index panel. The entry above in the subject line is a good illustration of this problem. I can barely read that entry.
Is there any way of changing these fonts?

Bill

In Konqueror: Settings > Configure Konqueror. There are 2 things I could find.
1: File Management > Views > Icons. Change it from "System Font" to "Custom Font" and change the font & size until it is something you prefer.
2: Web Browsing > Fonts. The Minimum size value is probably most interesting to you.

Note that change 1 affects Dolphin as well.

System Settings > Appearance > Fonts.
Head there. It allows you to change the size of every font displayed on your system, aside from in certain programs which will set their own size (Iceweasel for eg.).