ResX Sucks!
Shawn has 5 reasons to hate ResX files! He also has a ResXCop tool to help keep your ResX files .NET 1.0 compatible. I'm hoping the MSBuild team will have solved some of these issues.
In its default mode, it simply warns of the presence of binary (base64) data elements... in its aggressive mode (/v switch) it will remove those base64 elements, and also back-port any CLR references it finds to the specified value. For example, the
/v=1.0.3300.0
switch is useful for preparing a build to target .NET v1.0.