Are you ready to install Visual Studio 2015 Preview that was just announced. Make sure you have plenty of space.
If you plan to do Cross Platform development, Visual Studio will install several third party tools and SDKs for Android, Apache, Git, Java, Node and so on. Just for cross platform tools and SDKs, expect to have 6GB free space available.
Check it out.
If you don't plan to do cross platform development, I recommend you go back and remove these options from the installer.