Originally Posted by Okie
with either xterm or rxvt you can change the background color or foreground color (fonts) by adding the following to the command:
rxvt -bg black -fg white (same with xterm)
or whatever color combination you want
rxvt -bg MidnightBlue -fg Red (same with xterm)
one thing i like about xterm is you can change the font size by holding down CTRL and right clicking inside the xterm window, most of the time i use either xfce4's terminal or sakura which is a nice xterminal emulator too...
You can also change it in the mrxvt configuration file, normally ~/.mrxvtrc (see the mrxvt man page for alternatives). There's a sample file called mrxvtrc.sample, loaded during installation (location varies; try /usr/local/etc/mrxvt/mrxvtrc.sample, /usr/etc/mrxvt/mrxvtrc.sample or search for it) which you can copy to ~/.mrxvtrc and customise.
The defaults are set in Mrxvt.foreground and Mrxvt.background. If you are using Classes/Profiles (via mrxvt's -name option) then check the Classes section of ~/.mrxvtrc to see which profile number is nominated on the <class name>.initProfileList and set the colour in the corresponding Mrxvt.profile<n>.background etc.
The colour definitions look something like "#efd5c6". If you want to pick your colour interactively, the Gimp's Toolbox->"Foreground and Background Colors" tool will generate the (HTML) hex string for the colour you select and you can copy-and-paste it into ~/.mrxvtrc.