##First install all standard R packages. If you don't want them all, you want to pass a different vector
##of package names.
newpackz <- new.packages();
install.packages(newpackz,dependencies=TRUE)

##Now install bioconductor. This script is not publicly available through the bioconductor site;
##you need to read the getBioC code provided publicly and figure out the "all" option. 
source("http://bioconductor.org/installScripts/2.4/biocinstall.R") 
biocinstall(groupName="all")

##Now update all packages
update.packages(ask=FALSE)