[Rd] Rtools (Windows XP): what dir is meant by "R source directory"?

[Janko Thyson]

Dear list,

thanks for providing such a great thing as the Rtools! Everytime I 
install it, though, I'm somewhat "puzzled" when it comes to the section 
"Select R Source Home Directory" (32 bit and 64 builds).
Is the folder that I need to specify here
a) simply the root folder of my R installation (e.g. C:/R/R-2.13.0),
b) a subfolder of the above R installation folder (e.g. 
C:/R/R-2.13.0/src, C:/R/R-2-13.0/bin/src or C:/R/R-2-13.0/bin/i386/src),
c) or does this just come into play when I try to build R from source, 
i.e. the folder where I would put the R tar.gz file?

I always choose the paths C:\R\R-2.13.0\bin\i386\src (32 bit) and 
C:\R\R-2.13.0\bin\src (64 bit). Would this be okay?

Thanks a lot for helping me out on this,
Janko