first of all, the web config file is an xml file.. so you have your appsettings close, the file should be something like
<add key="ConnString" value="Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=ensurecms;Data Source=VENUS;"/>
anyway, since you are declaring a connection string, you should now that in 2.0 there is a conection string section in the web.config.
you can do something like this
<add name="ConnString" connectionString="Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=ensurecms;Data Source=VENUS;"
you should check the providername ;)
then is will be easier to connect datasources (since it will recognize the connectionstrings section) and by code using: