si has instalado la version MSDE (Microsoft Desktop Engine) , la version mas corta que hay, te recomiendo que instales ahi mismo (sin des-instalar nada), la version SQL SERVER 2005 EXPRESS EDITION WITH ADVANCED SERVICES y/o la version SQL SERVER 2008 EXPRESS EDITION.
http://www.microsoft.com/downloads/d...displaylang=es
No se te olvide aplicar el service pack 2.0