XML DataTable Concurrent Access

Question

I have a simple program using an XML file to store a single DataTable.  I've just learned, however, that multiple users(computers) will need to at least view this data concurrently.  Should I let the first instance of the program that accesses the file set it to Read-Only, and then others could check and realize they don't have Write Access??  Any ideas on the best way of accomplishing this would be greatly appreciated.  Maybe ASP.NET would be the easiest way to allow for concurrency?  Thanks.