Database engine installation failed Being asked to implement an application for purchasing management, the database managing system which I have to install, is SQL Server 2008.

I am having some issues while installing the main component, Database engine. 

I've searched a lot for my problem, I found out that during the installation, I have to use the account network service rather than system, and after uninstalling all the components, and then re-installing SQL Server. However it didn't do any better.

Just for the OS I am using, it's a Windows 7 Professional.
As for the message printed during the installation, i have :


  "Wait on the database recovery failed. Check the SQL Server error log for potential causes."


Any ideas where the problem can be ? or do i need another version of windows to install it ?
The answer was to create a user who would the super administrator of the database. So that we can distinguish between Windows authentication and Sql Authentication, in case it doesn't work !!! 
Thank you !