I was asked recently about when it would be appropriate to use InfoPath vs. Smart Documents. It's an interesting question as there is quite a degree of overlap between these technologies, so here are my rules of thumb for choosing between them...
Consider InfoPath when:
Consider Word SmartDocs when:
Consider Excel SmartDocs when:
Finally remember that since the underlying information set in all these cases is XML it's pretty easy to use a combination more than one of these techniques for different purposes. For instance InfoPath could be used to collect status reports from a number of people, which Word can then aggregate and display in a familiar format for management reports.