C caron character in R

Hi!
In R 1.6.1. for Windows using RGui interface I try to use characters of
Slovenian alphabet. Slovenia is a small Slavic country south of Austria
with 3 characters which are not found in English alphabet, namely C, S
and Z- all with caron. As S and Z are presented OK in both Console and
Graphics window, this is not the case with C caron, which is shown as E
acute- for an example please see:
http://www.sp.uni-lj.si/bojan/statuni/datoteke/temp/q.gif
(In RTerm problem is even worse - all characters are wrong. I don't want
to bother you with RTerm, because I rarely use it).
Any idea?