Problem with SQL Server Database in Visual Studio 2008

Hi, excuse me for my bad english, i hope that you understand and you can help me.
I have this problem:
I have Visual Studio 2008 and SQL Server 2008 but when i create an SQL Server Database i read that i need SQL Server Express 2005, Why????.....how can i resolve this question without install it but using 2008 version??
Thanks....;-)
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