If you’re getting started with Ruby on Rails, one of the better platforms to program in is Eclipse largely due to RadRails and the SVN plugin called Subclipse. Eclipse and the community versions of the plugins are free, so it’s definitely worth taking a look at.

This article is assuming that you have a working (but possibly outdated) version of Rails installed.
If not, and you’re running on Windows, I recommend searching for the InstantRails package and installing that first.
If you’re running Mac or Linux, you’ll need to install/upgrade Ruby to the latest version and then you can proceed with the following gem commands.

To Upgrade Rails:
gem update –system
gem update
gem update rails
gem cleanup

If you run into errors (possibly when you try and add your first rails project) try:
gem uninstall rails
gem install rails
gem cleanup

Eclipse:

Go to www.eclipse.org and find the latest version to download. The page is currently at:
http://download.eclipse.org/eclipse/downloads/drops/R-3.3.1.1-200710231652/index.php

Download the “Platform Runtime Binary (About 40mb)” for your Operating System.
Unzip this folder to whereever you want the install files of Eclipse to be.
Open the folder and find the Eclipse executable, and make a shortcut of it.
Move this shortcut into your start menu, desktop, or whatever you use to get to your programs.

Aptana Plugin:

Go to: www.aptana.com
Click on “get it now” for the community edition.
scroll to the bottom of the page and click “download” for the community edition.
click on the eclipse plugin tab
Click on download

In Eclipse: click on help, software updates, find and install.
Search for new features to install.
Click next
Click “new remote site”
Name it “Aptana”
Enter in the URL (which at the time of this writing is:
http://update.aptana.com/update/3.2/)
Follow the prompts, and select to download “Aptana” when it asks for it.

Subversion Plugin (called Subclipse):

http://subclipse.tigris.org/
Click on help, software updates, find and install.
Search for new features to install
Click next, then “new remote site”
Name it “Subclipse”
Enter in the URL found on the Subclipse website. Currently it is:
http://subclipse.tigris.org/update_1.2.x

Follow the prompts, but uncheck the integration box because you don’t have those plugins installed.

Click Install All and Restart Eclipse when it asks you.

Aptana Rad Rails:

Open Eclipse
On the Aptana Home Page (must have Aptana installed first), at the bottom of the Languages section, there’s a link to install Aptana RadRails.
Uncheck the Ruby Mylyn Connector Feature.
Follow the prompts, install all, reboot Eclipse when it asks you.

Show SVN Repository:

In Eclipse, click on Window, Show View, Other.
Open up, SVN folder, click on SVN Repository, Click OK.

Add Rails and Rake Paths to Eclipse:

Click window, preferences, click on plus sign next to Rails, click on Configuration. Browse to your rails files.
On my Windows computer, (using the Instant Rails package), the paths were at:

C:\InstantRails\InstantRails\ruby\bin\rails
C:\InstantRails\InstantRails\ruby\bin\rake
C:\InstantRails\InstantRails\ruby\bin\mongrel_rails

Of course, this totally depends on where you installed Ruby.

Click Apply to save them.

Other Eclipse Configuration Options:

Click window, preferences.
Click on Team, SVN
Check “Select unversioned resources on commit”
Click on Apply.

In the preferences window, click on “Team”, “Ignored Resources”, Add Pattern.
Add “.project” and “.log”. If your computer saves that annoying Thumbs.db file, you might want to ignore that one too.

Good luck, and I hope this was useful to you.