Microsoft SQL Server 2008 R2 Express Parallel Installation

Hi,
This is a pretty noob question,
I want to install Microsoft SQL Server 2008 R2 Express parallel to my current installations. but the document at
http://www.microsoft.com/download/en/details.aspx?id=23650
doesn't cover my specific case.

Here is my Microsoft SQL Servers currently installed on my computer:
Under C:\Program Files (x86), I have
Microsoft SQL ServerMicrosoft SQL Server Compact Edition and under C:\Program Files, I have the following as well:
Microsoft SQL ServerMicrosoft SQL Server Compact Edition From the start menu, I can access
Microsoft SQL Server 2008Microsoft SQL Server 2008 R2
They all pointing to the Microsoft SQL Server on my corp network.
Now, I want to install the Microsoft SQL Server 2008 ...