How can I convert obsolete word processor files and preserve formatting?
for WordPerfect documents, you can also try to use OpenOffice, LibreOffice, NeoOffice (...), libwpd filter (see http://libwpd.sourceforge.net/features.html ) will then be used to convert the document in odt format.

For WriteNow files, the best solution is probably using an emulator. If you have access to a 64 bit Intel Mac with OsX 10.6 ( or 10.7), you can also find on http://sourceforge.net/projects/libmwaw/files/ a precompilated version of a WriteNow filter to odt : mwawOSX.zip ; ie I tried to write a small filter to convert WriteNow files, it works "well enough" on the few WriteNow files that I had found, so maybe it can work also for your files ( or maybe not :-~ ).