First of all, it requires a 64bit version of Windows 2008 Server, and I didn't know that when I have to. After installing that, you'll need to install SQL Server, and I installed, again, the 2008 Standard version. Having the operating system and SQL server installed, is not enough for a smooth VCenter installation. You'll also need:
1. create a database for VCenter, and an owner for it, of course, with a password.
1. create a System DSN for VCenter to use to connect to your SQL Server - don't use "SQL Server", use "SQL Server Native Client", and set the user to be the newly created one, and the default database to be the newly created VCenter database.
3. disable Full recovery - in SQL Server Management Studio > right-click VCenter database > Properties > Options > Recovery Model > Simple (instead of Full)
This will grant you a smooth VMWare vCenter 4.1 installation.
[update] To install vCenter Update Manager, you'll need to create another pair of username/database. But, this time, you'll need to create a 32 bit System DSN. This is done like this:
Start > Run > c:\windows\SysWOW64\odbcad32.exe
This utility creates 32 bit System DSN on a 64 bit operating system. That's all, for now..