Since VCenter 4.1, installing on a x64 machine is different. The major difference is that you now need a 64 bit System DSN, but which is not so easy to set up using the normal odbcad32.exe. You need the SQL Server 2008 Native Client before the VMWare VCenter 4.1 installation recognises your System DSN.

1. Install Windows Server 2008 x64  – not R2, which is not supported yet;
2. Install SQL Server 2008 R2 x64 on a Windows Server 2008 R2;
3. Create a database for VMWare on this SQL Server, and modify the rights and logins accordingly;
4. Get the Microsoft SQL Server 2008 x64 Native Client from Microsoft and install it on the machine you want to install VCenter on;
5. Set up X64 c:windowssystem32odbcad32.exe system dsn pointing to the created database;
6. Start SQL Agent service on SQL Server;
7. Install VCenter 4.1