Is it possible to use Windows Authentication to connect to a SQL Express db?

I've been looking around to find an answer to this question, and seeing lots of different ans开发者_开发问答wers, some of which don't look right to me. Here's my problem.

I've created a SQL Server 2008 Express database, and populated it with tables from 2 regular SQL Server databases (it's to receive data from the 2 databases). I've done this using Windows Authentication.

Now I want to test deploying an app, as a ClickOnce application, so I've written a bare-bones console app in VS 2010. Next I tried to add a new data source to the SQL Express 2008 database. But when I try to do that I get a message saying, "This file is in use. Enter a new name of close the file that's open in another program." (I'm running VS 2010 as an administrator on my Windows 7 Ultimate box, which was one of the answers someone gave to fix this problem, but isn't working for me.) I don't have the SQL Express db open in SSMS or anything else. One solution I've read is to get into SSMS and detach the .mdf, but then how would I do maintenance, like create new SP's, views, etc? Is it a maintenance nightmare of attaching in SSMS while not in VS 2010, do DBA work, then detach the DB, get into VS 2010 do work, etc?

The database is meant to run on the user's machine; not a network share.