Install SpringsSource Tool Suite Plugin for Eclipse Galileo / Helios

Eclipse is used in my machine to develop PHP, standard Java, GAE based, and Spring framework applications. In order to keep only one instance of Eclipse, I preferred to install Springsource Tool Suite as Eclipse plugin instead of downloading whole new STS package.

Environment : Fedora Eclipse Helios default installation. Fedora 14.

Add Springsource Tool Suite Milestone Update Site
a. Download one of the following bookmarks file suitable for your Eclipse version and save it to your system :
• Eclipse Galileo 3.5: http://dist.springsource.com/milestone/TOOLS/composite/e3.5/bookmarks.xml
• Eclipse Helios 3.6: http://dist.springsource.com/milestone/TOOLS/composite/e3.6/bookmarks.xml
b. Open Preferences > Install / Update > Available Update Sites in Eclipse.
c. Click the Import button and select the downloaded bookmarks.xml. Click Open to finish the import.
d. Verify that the dialog list the following update sites as enabled.
Eclipse 3.5
• Galileo (http://download.eclipse.org/releases/galileo)
• SpringSource Update Site for Eclipse 3.5 (Milestone) (http://dist.springsource.com/milestone/TOOLS/update/e3.5)
• SpringSource Update Site for Eclipse 3.5 (Milestone, Dependencies)
(http://dist.springsource.com/milestone/TOOLS/composite/e3.5)
Eclipse 3.6 :
• Helios (http://download.eclipse.org/releases/helios)
• SpringSource Update Site for Eclipse 3.6 (Milestone)
(http://dist.springsource.com/milestone/TOOLS/update/e3.6)
• SpringSource Update Site for Eclipse 3.6 (Milestone, Dependencies)
(http://dist.springsource.com/milestone/TOOLS/composite/e3.6)
e. If those update sites are correctly listed close the preference pane by clicking “OK”.

Install Springsource Tool Suite Plugin
a. Open the update manager from Help > Install New Software
b. From the Work with drop-down select the update site with the name SpringSource Update Site for Eclipse 3.5 or SpringSource Update Site for Eclipse 3.6 depending on your Eclipse version.
c. Select the components as shown in the following screenshot:

Make sure that all others settings remain as shown on the screenshot. Note: It is also possible to only install a subset of all available features.
d. Click “Next >” to start the installation process.
e. Click “Next >” on the Install Details wizard page.
f. Select “I accept the terms of the license agreement” on the Review License
wizard page and click “Finish”.
g. This will now start the installation process and download all required
components.
h. Click “OK” on the Security Warning dialog.
i. Restart Eclipse when prompted in the Software Updates dialog to finish the
installation.

Verify STS Plugin Installation
Open "Help > About Eclipse Platform". If installation process succeed Spring IDE and SpringSource logo should appeared as below :

Spring IDE and SpringSource logo marked by  red.

Disable STS Plugin
According to eclipse FAQ plugin should not be removed, they should be disabled instead (http://wiki.eclipse.org/FAQ_How_do_I_remove_a_plug-in%3F). However I found out that there is Uninstall button in my Eclipse installation. To uninstall STS plugin do following :

1. Go to Help > Install New Software
2. Click what is already installed ? link in bottom right of pane.
3. Make sure Installed Software tab is chosen.
4. Select all Springsource Tool Suite plugin.
5. Click Uninstall button.
6. In next pane, click Finish button to confirm uninstallation of previously selected plugins.
7. In Preferences > Instal/Update > Available Software Sites disable all Springsource milestone update sites.

Select all SpringSource Tool Suite plugins

Source
http://download.springsource.com/release/STS/doc/STS-installation_instructions-2.5.0.M3.pdf