I was able to add the launch condition but there's a small issue. I do not know if I am wrong or is it a .net issue or Mind Manager issue.
I check for FILEEXISTS in the launch condition with Mindmanager.exe as file. The Min version value is set to 6.1.809.0. I have this version installed and this did not work.
A kind of hack, I just changed the Min version value to 6.1.808.0 and it works. My problem is solved (unless there's a MindManager version 6.1.808.0).
But thinking deeper,should not the min version should be checked?

I agree that this is not really intuitive.

To detect the version match Windows Installer uses the same algorithm as for file overwriting. This means: if the existing version of the file is identical to the version you specified in your setup, it compares the language. Only if theversion of the existing file is higher than the MinVersion in your setup it will ignore the language.

This is documented in MSI help topic Signature Table at http://msdn.microsoft.com/library/en-us/msi/setup/signature_table.asp(see the note for MinVersion)

I agree that this is not really intuitive.

To detect the version match Windows Installer uses the same algorithm as for file overwriting. This means: if the existing version of the file is identical to the version you specified in your setup, it compares the language. Only if theversion of the existing file is higher than the MinVersion in your setup it will ignore the language.

This is documented in MSI help topic Signature Table at http://msdn.microsoft.com/library/en-us/msi/setup/signature_table.asp(see the note for MinVersion)

Thanks Stefan. The link was of great help, and now I can feel relieved that I had done the correct thing.. (though I did not know it).....