The team programming computers all run debian and our package containing the compiler is for it which means that it will be easier for anybody who wants to test code on their own computer to use debian too. The easiest way to install debian is to use the netinst cd image. The download page is at http://www.debian.org/CD/netinst/ and the current version as of 11/14/11 is http://cdimage.debian.org/debian-cd/6.0.3/i386/iso-cd/debian-6.0.3-i386-netinst.iso. After you get debian running, you'll have to install some basic packages in order to compile code. You can install packages from the command line by typing "apt-get install packages" as root where packages is a space-separated list of packages you want to install. The ones that I can think of are grep, sed, wget, ssh, make, subversion, gawk, gcc, g++, bash, ruby, unzip, patch, ncftp, and vim. You will also need to download and install the package we have for the vxworks cross compiler. It is currently at a temporary location and will eventually be at some other more permanent location. You can install it with "dpkg -i powerpc-wrs-vxworks_4.5.0-1.0_i386.deb" in whatever directory you downloaded it to (you'll need to do that as root).
Please look at the SVN Usage page for tips on using SVN well. The URL for the 2011 code is svn://boardsailor.com/frc971/2011/trunk/src. After you check it out, you will have to do a "make" in externals to build WPILib (that will also make sure that your setup is working). Once you do that, you should be able to build the robot code (it's in packages, in which README.html is more current than README.txt).
After you check out a new working copy, you'll have to do a "make" in externals to download WPILib. After you do that once (and it succeeds, you'll need an internet connection), you can just do a "make" in packages to rebuild the code.