Sweave

Hello,
I never used Sweave before but now I try and got:

 rnwfile <- system.file("Sweave", "example-1.Rnw", package = "utils")
 Sweave(rnwfile)

Writing to file example-1.tex
Processing code chunks with options ...
 1 : echo term verbatim
 2 : term verbatim pdf
You can now run (pdf)latex on 'example-1.tex'

 tools::texi2dvi("example-1.tex", pdf = TRUE)

Error in tools::texi2dvi("example-1.tex", pdf = TRUE) : 
  pdflatex is not available

The code is from Sweave.pdf file in utils/doc
I am using R-2.13.0 in Win7  Toshiba laptop
Please any help?

R.Heberto Ghezzo Ph.D.
Montreal - Canada