I've been meaning to do a quick blog article about this for some time so I don't forget. I found setting up DasBlog on Windows Server 2008 pretty difficult. I currently run DasBlog on a Windows Server 2008 server with the following app pool ".Net Framework v2.0 Application pool in Integrated Mode"
One of the issues I discovered was setting up the permissions so that DasBlog could read and write the to the content folders. To do this follow the steps you find here http://learn.iis.net/page.aspx/624/application-pool-identities/
Basically you need to give the Application Pool that DasBlog is running under, permission to these folders. So for example setting permission on the content folder to allow the following user IIS AppPool\[your app pool name] read and write access.