After a successfull installation of the SQL Server 2008 (aka Katmai) June 2007 CTP version on Windows2008 Beta3 system, I realized that the client components are missing. I do not remember that I got an error message during the SQL Server 2008 installation.
So, I tried to run the client tools installation by running the setup.exe application under the tools folder where the installation files reside.
But then I got the following error message :
Windows Installer
This installation package could not be opened. Verify that the package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer package.
After then I tried to run the sqlrun_tools.msi installation package which is on the folder \tools\setup. This is one folder deeper than the previous try. This time installation package run successfully and then the following message stopped the installation and cause it fail.
Microsoft SQL Server Setup
Setup has detected SQL Server 2005 Client Components on the computer where you are installing SQL Server "Katmai". SQL Server "Katmai" installation is not supported side-by-side with SQL Server 2005 Client Components. You must either install SQL Server "Katmai" Client Components on a different computer or uninstall SQL Server 2005 Client Components before installing...
So if you plan to use the client tools of the SQL Server 2008 with its database engine and with the previous SQL Server 2005 installations, you should think once more to install the SQL Server 2008 on an other computer. Or remove the SQL Server 2005 client components before SQL Server 2008 client components.
I tried the difficult path and tried to remove the SQL Server 2005 client components.
How to uninstall the SQL Server 2005 Client Components :
In order to remove the client components, I opened the Control Panel and select the "Uninstall a program" In the list of installed programs I selected the "Microsoft SQL Server 2005". When the Microsoft SQL Server 2005 Uninstall dialog box is displayed I only selected the Workstation Components from the common components region of the screen. And then the uninstallation of the client components is successfully completed. But before trying to install the Katmai client components, restart the server since I got an error message which is indicating something is preventing the installation to complete. So give a chance to your server to clean up the remainings of the uninstalled components.
After the restart is completed and the server is up again, run the \tools\setup\sqlrun_tools.msi and finish the installation of the client components of the SQL Server 2008 CTP June 2007.
Using the new SQL Server Management Studio (SSMS) you can both connect to SQL2005 instances and SQL 2008 instances.
Note : I experienced a similar problem which is indicating that there setup has detected one or more instances of SQL Server 2000 on the server where SQL2K8 installation is being done during the installation of July CTP release. But this time I had to remove registry key entries that remain in the registry even after uninstallation of SQL2K instances. You can read article titled Setup has detected one or more instances of SQL Server 2000 on the computer where you are installing SQL Server 2008 and read details about deleting the registry key "My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\80"