Hi dalethom and welcome to our forums!
I'm not sure where SharePoint comes into play here, but one idea is to expose your SQL2005 sprocs as a web service. After this is done, you can hook up to the web service in InfoPath as a secondary data source and submit/receive all you want. It's not an easy task that you are pursuing, but it should be doable. Let us know if you hit any problems!
http://msdn2.microsoft.com/en-us/library/ms345123.aspx
Good luck!
Matt Faus / Microsoft InfoPath MVPQdabra® Software / Streamline data gathering to turn process into knowledge