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You could use srvany to run IISExpress as a service.
Here is a blog post about this (though I haven't tested it yet, it looks promissing).
http://arvinboggs.wordpress.com/2011/04/08/installing-iisexpress-as-a-service-on-windows-2003/
The interesting part is where you pass a /config ... parameter to iisexpress, otherwise IIS Express loads the config from the users documents folder.
If you want your IISExpress to be able to be reachable from remote machines you can either