I really liked the no hassles way Biocnoductor has put a cloud AMI loaded with RStudio to help people learn R, and even try using R from within a browser in the cloud.
Not only is the tutorial very easy to use- they also give away 2 hours for free computing!!!
Check it out-
and wow! I am using Google Chrome to run R ..and its awesome!
Interesting- check out two hours for free — all you need is a browser and internet connection