The last time I installed Eclipse on my PC (Windows 7 64-bit) I experienced the same issue. The workaround that finally made Eclipse work again was to put all the IDE's files in C:\Windows\System32. Why don't you try this?
Take the IDE's file and decompress it into System32, make sure you don't decompress it into a subfolder within System32. Then start devkit-launcher.bat with Admin rights and it should work.