There is no visible difference between Nimbus Roman No9 L italics and bold italics on the screen, but there is a difference on the printout. The same (almost) for the regular vs. bold face. At least in KWord, AbiWord and partly in standard OpenOffice - however it works all right in OpenOffice-Ximian! There is also no possibility to choose between the condensed and normal typefaces of Nimbus Sans L.
If you can still reproduce this w/ media-fonts/urw-fonts-2.1-r2, then report this upstream. We are not writing fonts, just distributing them.