Since the 2007-05-25 version, Kicad (which uses unicode strings) can run under W98,
if the library unicows.dll is found by kicad.

If you want to use kicad you must download unicows.dll,
and copy it in Windows or kicad/winexe directory.
Because many others programs use unicows.dll, this can be already done.

But kicad is NOT tested under W98.
A known problem is incorrect printing
(However, you can plot a postscript file, and use gsview to show and print it)
