How to install SQL Server Management Studio Express 2008

In the SQL Server 2005 installing of SSMSE (SQL Server Management Studio Express) was very easy, just all about launching the installation file. In the SQL Server 2008 process of installing SSMSE is a bit different, since installation is represented as a part of the SQL Server Installation Center Utility.
In order to install SSMSE 2008 you need to perform the following steps:

1. Download the installation package and launch it.
2. Click "New SQL Server stand-alone installation or add features to an existing installation".
   
3. Wait untill installation setup support files and configuration checks, then click OK and Install.
4. Click "Perform a new installation of SQL Server 2008", but not "Add features to an existing instance of SQL Server 2008" (!!!).
   
5. Click Next in the Product Key dialog even if all the options are disabled.
   
6. In the feature selection dialog enable Management Tools feature and click Next.
   
7. Wait untill installation performs an additionnal configuration checks. Then click Install. Note: You might receive a configuration error, if you have SQL Server 2005 Express tools already installed on the machine. In my case I removed SQL Server 2005 Express tools. But it was not enough. I also used solution provided here (removing registry key). It was helpfull.
   
8. Wait untill installation completed. Enjoy!