Nice to see some quick and easy install directions. I would add, however, that most people are going to need a lot of the add-on packages that don't get installed by default for a lot of the cool things that can be done. Can I suggest you add directions for how to install packages too?

Here are a couple examples:

install.packages(c("rpart", "ggplot2", "rattle", "rpart.plot", "randomforrest"))
Or, the user can click on the empty box next to the package in the lower right side in R Studio to do the same thing.

I like to keep an R file with a line of code noting all the various packages at the top so everything I need is easily portable to someone else without them having to figure out what packages they might need for the code being given to them.

For mac users, I would also add that for some packages you will need some additional software to be installed. As an example, for the package "rattle", I had to have "RGtk2" and RGtk2 required me to install XQuartz and macports which are completely separate from R and R Studio, but required none the less.

Also note that if you are installing while on a corporate network, you might also run into issues that are related to ports being blocked by your corporate network. I had that problem too with several packages and had to use my personal hotspot on my iphone to connect to install to get around the issue.