没装Sql Server 2005 Express就不能使用webpart控件？

VS 2005 Pro版，装的时候c盘空间不够了
而sql server 2005 express居然不让我选择路径！
于是只好舍弃不装

结果今天在使用webpart的时候死活报“不能连接到sql server”
我只是拖了个webpart manager上去而已
还没干任何事呐

An error has occurred while establishing a connection to the server.  When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

SQLExpress database file auto-creation error:

The connection string specifies a local Sql Server Express instance using a database location within the applications App_Data directory. The provider attempted to automatically create the application services database because the provider determined that the database does not exist. The following configuration requirements are necessary to successfully check for existence of the application services database and automatically create the application services database:

1. If the applications App_Data directory does not already exist, the web server account must have read and write access to the applications directory. This is necessary because the web server account will automatically create the App_Data directory if it does not already exist.
2. If the applications App_Data directory already exists, the web server account only requires read and write access to the applications App_Data directory. This is necessary because the web server account will attempt to verify that the Sql Server Express database already exists within the applications App_Data directory. Revoking read access on the App_Data directory from the web server account will prevent the provider from correctly determining if the Sql Server Express database already exists. This will cause an error when the provider attempts to create a duplicate of an already existing database. Write access is required because the web server accounts credentials are used when creating the new database.
3. Sql Server Express must be installed on the machine.
4. The process identity for the web server account must have a local user profile. See the readme document for details on how to create a local user profile for both machine and domain accounts.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

不知道啥毛病