[R] Help: Upgrading to R2.5 on Ubuntu (Feisty)

[M. Jankowski]

Thank you in advance for reading this help request. I am pretty new to
R. I am experiencing some issues getting 2.5 installed on my Ubuntu
Fiesty system and
seek your advice.

To the best of my ability I followed the instructions here:

http://cran.r-project.org/bin/linux/ubuntu/README

Setting this as the last line in my sources.list:
deb http://cran.fhcrc.org/bin/linux/ubuntu feisty/

When I typed in:

mdj at lapmdj:/usr/local/lib/R/site-library$ sudo apt-get install r-base
Reading package lists... Done
Building dependency tree
Reading state information... Done
r-base is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
mdj at lapmdj:/usr/local/lib/R/site-library$

But when I go to R and check my version:

> version
              _
platform       i486-pc-linux-gnu
arch           i486
os             linux-gnu
system         i486, linux-gnu
status
major          2
minor          4.1
year           2006
month          12
day            18
svn rev        40228
language       R
version.string R version 2.4.1 (2006-12-18)
>

My version is still 2.4.1. I must be missing something. What do I need
to do to get R version 2.5 installed on my ubuntu feisty (7.04)
system? Let me know if there is any additional information I need to
give to be helped out with this.

Thank you for taking a look at this,
Sincerely,
Matt