Primavera BSS ERP Express error during the install

Hi,
During the install of Primavera BSS ERP Express Edition this error appears and if I press the OK button the install is rolling back. I meet all the system requirements for this program and the installer is compatible with my Windows XP. So, is there a problem with my PC or with the installer ? How should I proceed next ?
Thank you !

Nao foi possivel instalar o SQL Server 2008 Express. Devera efectuar a sua instalacao manulmente, a partir da pasta ‘C:ProgramasFicheiros comnusPRIMAVERASGX750SQLExpress’ no final desta instalacao
OK
