Unfortunately there are no good free options for reading .doc and .docx files. Even commercial options are sparse at reasonable prices, but there are good extremely expensive options.
For reading .doc files the only free option I'm aware of is POI for Java which you can run in .NET using IKVM. However, Word support in an experimental branch of POI's SVN repository, so I don't know how well it works.
http://poi.apache.org/
http://www.ikvm.net/
If you just want the text out of the .doc file and don't care about formatting, you can use the IFilter Win32 interface through pinvoke.
For reading .docx files you can use Microsoft Office Open XML SDK. Don't let "SDK" fool you though, this is a very light abstraction over the dealing with the XML directly. It's almost as painful to use.
http://www.microsoft.com/downloads/en/details.aspx?FamilyId=C6E744E5-36E9-45F5-8D8C-331DF206E0D0&displaylang=en