I've been meaning to post something about R for a while, but never got started, and now have a pile of things I'd like to post, so it's time to get started.

I first started using R during my Master Dissertation where I had to do some stats.  I've since had several occasions needed to do some ad-hoc data analysis of one sort or another, and every time I've ended up using R to get it done.  I now use R regularly, and while can't describe myself as an expert, I'd say a enthusiastic amateur.

R is an integrated suite of software facilities for data manipulation, calculation and graphical
Display.  It is a full, proper programming language, even being turing complete.  It has a suite of operators for calculations on data in many forms, in particular arrays and matrices.  It also has an enormous collection of add-on packages for pretty much any form of analysis, calculation or statistic that can be performed.

You can run R in a million different ways, the most basic is just using the basic R interpreter and the command line.  Personally I use Eclipse / StatEt / LaTex, which I'll describe another time.

A colleague recently asked about the basics, so I've cribbed my email back to him here, where I suggested either Rcommander or JGR / Deducer, which both seem the ideal mid point of some extra menu/click functionality without trying to rebuild Excel in R.  Rcommander seems to be slightly better in terms of a statistics tool, and JGR/Deducer in terms of data exploration.
 
RCommander (http://socserv.mcmaster.ca/jfox/Misc/Rcmdr/) is an add-on package to R.

To Use RCommander, install R and run, then in the console, type
install.packages("Rcmdr", dep=TRUE)
this should install R commander.  To run it in the console type

 install.packages("Rcmdr", dep=TRUE)

this should install R commander. To run it in the console type

library(RCmdr)

JGR (Java Gui for R - http://rforge.net/JGR/ ) and an add-on to it, Deducer (http://www.deducer.org).  They're both 'packages' in R, which means some extra functionality that can be easily installed from within R and then used.

To Install
Ensure you have a fairly up to date Java installed
Download and Install the latest version of R from CRAN (Comprehensive R Network -
http://cran.r-project.org/ )
Download and Install the JGR client from http://rforge.net/JGR/
Start the JGR application.  It will get any extra things it needs.
The JGR console should now be open. To load Deducer, go to 'Packages & Data' > 'Package Manager' and select Deducer and DeducerExtras.
 
Now you're using R !
 
Now you need to go find some help, I'd recommend some places to start with R;