saving graphs; jpeg(), bitmap()

Dear Mac R-users

I want to export some plots. I have looked in the documentation and in 
the R-help archives. 2 main functions jpeg(), bitmap() are used, but I 
can't save any plots using them. (error logs at the end of the email). 
I'm using a PowerBook G4, Panther 10.3, R.2.1.

a) when using jpeg() I seem to be missing the X11 server. I have X11 
on my computer and it works fine. (XDarwin 1.3b4). On the R menu, 
under Miscillaneous there is a Run X11 server. When I lauch it reports 
an error:  "2004-12-08 22:24:13.082 open[10513] Couldn't launch 
application:  X11.app"

b) for using bitmap() I don't have the ghostscript file. Is it a mac 
file? Should I get it from somewhere?

c) I saved the files from the quartz device with the menu function. 
This solves the problem somewhat, but: I would like to save jpeg 
files. Even if I save pdf I would like to write it in a script. pdf() 
should do it, but I can only produce files with zero bytes using it...

d) and this is really just curiosity. The pdf file exported via menu 
is small (16kb) but when I open it in Photoshop and tell it to be 
300dpi becomes a big file (14Mb) and the quality is very good! I 
imagine this to be related to vectors instead of dots. I googled the 
terms, but there's nothing that mention pdfs as good grahp formats (I 
didn't do an extensive search, there were MANY documents, even trying 
to be very stringent)

#####################
errors
jpeg('pic1.jpg')
Error in X11(paste("jpeg::", quality, ":", filename, sep = ""), width, 
 :
	unable to start device JPEG
In addition: Warning message:
unable to open connection to X11 display`'

bitmap('temp.jpg', type='jpeg', res='300')
/bin/sh: line 1: gs: command not found
Error in bitmap("temp.jpg", type = "jpeg", res = "300") :
	Sorry, gs cannot be found