My .Rprofile that works both on Windows and Linux

Rprofile.R

# .Rprofile -- commands in this file will be executed at the beginning of
# each R session. On Windows, the R_PROFILE environment variable must have value
# with the full path to this file. On Linux (or other Unix like systems) this file
# must be in the user's home directory.

# Set the default repository to the main CRAN site
options(repos=c(CRAN='http://cran.r-project.org'))

# Set the oDrive varaible and library path
if(Sys.info()['sysname'] == 'Windows') {
	oDrive = 'o:/'
	.libPaths(paste(oDrive, 'R/library/Windows', sep=''))
	require(utils, quietly=TRUE)
	print("Setting memory limit for R to 4GB...")
	memory.limit(size=4095) #Set to 4GB (for 64-bit Windows, this can be much larger)
	message(paste('R_LIBS:    ', Sys.getenv('R_LIBS'), sep=''))
	message(paste('R_PROFILE: ', Sys.getenv('R_PROFILE'), sep=''))
} else if(Sys.info()['sysname'] == 'Linux') {
	oDrive = '/n01/OutcomesAssessment/'
	.libPaths(paste(oDrive, 'R/library/Linux', sep=''))
} else if(Sys.info()['sysname'] == 'Darwin') {
	oDrive = NULL
}

# Customize the default look and feel of ggplot2
if(require(ggplot2, quietly=TRUE)) {
	theme_update(panel.background=theme_blank(), 
				 panel.grid.major=theme_blank(), 
				 panel.border=theme_blank())
}

# On Linux we will alter the default behavior of the makeR package.
if(Sys.info()['sysname'] == 'Linux') {
	if(require(makeR, quietly=TRUE)) {
		setAutoOpen(FALSE)
		setDefaultBuilder(builder.rnw.native)
	}
}

# Change the location of the SQL repository
if(require(irutils, quietly=TRUE)) {
	setSQLRepos(paste(oDrive, 'R/ecir/data', sep=''))
}