I've blogged about FileHelpers before. I like it a lot.

Since then, Marcos has added even more great features to it including support for .NET 2.0 Generics and a new Wizard application that really increases the speed in developing new records.

Marcos has an article up on CodeProject as well as a FileHelpers website with examples and a support forum.

Seriously, if you're still using String.Substring calls to parse out flat files, give the library a try.