I recently added SVN to eclipse on a couple machines for an upcoming project. You can find the basic instructions here under the Ganymede Release.
For the most part those instructions were fine, but I ran into a an issue on one of the machines. I could not get Ganymede/Collaboration Tools to come up as an option within Software Updates. To solve this, add the following site manually:
Once you have the basic SVN installed, update the following two sites as well:
And now you should be good to go. I am not sure why one machine acted differently since they are both have the same hardware and operating system. It could have just been a fluke, but I wanted to post this in case someone hit the same issue (or if I needed the links again :P ).