This is a solution rather than a question. I am running Windows 7 Enterprise (V. 6.1, build 7601, SP1). I had followed the instructions at http://wiki.lyx.org/uploads/LaTeX/SweaveR/lyx_with_r_and_sweave_instructions.pdf, and while both versions of the batch file worked from the command line, LyX couldn't get past generating the noweb file.
I finally tracked down the solution. The converter command (step 8) has to be "Rweave.bat $$i" rather than "Rweave $$i". Bruce
