As far as searching across a network thats really not going to be easy to do for security reasons. You would have to give all of your drives rights for the IUSER account to search/open files which would leave you completely vulnerable to attacks.
I would suggest a different route, but don't know of any to tell you.
I don't think the FileSystemObject would really work since you would need to be able to handle the Word format. Additionally, it would take a lot of work to build a searching engine that could handle relevancy and ranked listings. A far simpler way to go is to use Index Server. Index Server will scan many types of documents and return your results in a ranked order.