After downloading eclipse after opening, select Help - Install New Software - Available Software Sites
Site name: Force.com IDE location: http://media.developerforce.com/force-ide/eclipse42
Select Force.com IDE and Next either at the bottom of the window currently or just before finishing the install and error message displays stating:
force.com ide 18.104.22.168309101331 (com.salesforce.ide.feature.feature.group 22.214.171.124309101331) requires 'org.eclipse.update.ui 0.0.0' but it could not be found
This happens via the Eclipse site and with the built in marketplace.