>Has anyone got any suggestions on how the app could be written to make it easier to re-write in the futre.
>
>I'm thinking along the lines of keeping UI code in the forms, and data-manipulation in separate objects, and not allowing one to directly "dabble" with the other.

That sounds like a good start. If it 'may one day' be built as 3 tier, why not make that day today? There's a slight performance overhead, but running a 3 tier system on a single tier does work. I'm using the Mere Mortals framework to develop this way.

Chris.