How should multiple processes on different Windows PCs use concurrently a file, stored in a shared directory?

Question

Problem:

I have multiple instances of the same C# application running on different PCs (OS: Windows XP, Windows 7) in the same LAN. I have to share some configuration data among them. Each process must have read-write access to the data. My employer insists on storing these shared data in a file, which is in a shared directory on one of these PCs.

Possible solutions:

1. Exclusive file opening: The data is stored in a TXT file (serialization to and from a binary file is also an option). Each process uses File.Open with FileShare.None when trying to open the file. Getting an IOException means that the file is already in use, so the process has to wait and try again later.
2. SQL Server CE embedded DB: The data is stored in an SDF file. The engine can handle at most 256 simultaneous connections (v3.5 SP2), which is more than enough.
3. SQLite embedded DB: The data is stored in an SQLite DB file. The documentation says SQLite works, but may be unreliable when used on a network share.
4. Other?

What is the preferred way to do this?