InfoPath Dev

I need to pass a value in a text box as a parameter to a web service. The value returned from the web service then needs to be displayed in another text box. Example: pass in ID from text box to the web service which then returns the social security number. That returned number is then displayed in a separate text box.

If you've set up a data connection to the web service, its data source should have a QueryFields section with fields for all the parameters.  Just use a rule on the textbox or a button to copy that textbox's value to the appropriate query field.