[R] image quality of plot inserted into PowerPoint

[Juan Lewinger]

Dear R-helpers,

I need to insert an R (2.6.0) generated plot containing semi-transparent colors into PowerPoint (2002). When I directly paste it from the clipboard or insert it as (enhanced) Metafile (I'm on Windows XP) the semi-transparent colors don't show. When I insert it at as a Bmp, Png or Jpeg and then convert to PDF the semitransparent colors do show but the quality of the image is not good enough when I zoom in at say 300%  (I'm making a poster for a meeting so being able to scale up is crucial)  

Any suggestions?

You can download the PDF file containing the four images corresponding to the original Png, emf, Bmp, and Jpeg formats from
 
http://www.4shared.com/dir/4240403/ce1af03d/sharing.html

Also, 1) for the emf generated image look at the little circles at the bottom of each boxplot: the fill color has bled out. Why? 
2) From the console menu I cannot save a plot as PDF (no file is saved when I try)