You must use Eclipse 3.2 or newer.
To check the Eclipse version use menu Help > About. In the snapshot the Eclipse version is 3.2.
You must use Java 1.5 or newer.
To check the Java version use menu Help > About, then click on Configuration Details. In the snapshot the Java version is 1.6.
To check the DVT plugin is installed use menu Help > About. You should see the DVT button.
To see more details, for example the version, you click the button.
To check the DVT license go to menu Window > Preferences and inspect the DVT > License.
The DVT license is pointet to by $DVT_LICENSE_FILE system variable.
