[R] Updating to R 3.1.1. - impacts on existing packages

[Sun Shine]

Hi list

I've signed up for a Coursera course on exploratory data analysis, and 
the recommendation is to update to R base 3.1.1. I'm currently on 3.0.2.

If I do upgrade, what is the best way for me to upgrade all my packages 
for compatibility? Would this be accomplished through the command:

 > update.packages()

Also, any ideas what percentage of the packages have been updated to 
work with 3.1.1. ? I'm just wanting to do a risk evaluation because I 
don't want to lose access to packages such as ggplot2, sna, statnet, 
FactoMineR, and several others through upgrading.

Thanks for any steers

Sun