Check for SQL Server Management Studio Version

Hey Guys

I need some help. I am doing a silent install of SQL Server 2008 R2 Express Edition with Tools but it wont install with SQL Management Studio 2005 Express on the computer.

I am looking for an easy, reliable way to tell which version of SSMS is currently installed on the machine. I am using NSIS to launch the install and I am hoping there is some flag I can use to :

• Get Version information (ie 2005,2008)
• Get Uninstaller (so I can Uninstall it if its the 2005 version)

Thanks