InfoPath stores data in XML or a database. SQL Server and Access are
supported by InfoPath, i.e., you can bind a form directly to either one of
these databases. Other databases such as Oracle can be accessed through web
services.

The same goes for data retrieval. Full support for stored procedures can be
achieved through managed code in InfoPath or by calling them through web
services.

Some resources for more information:
http://msdn.microsoft.com/library/en-us/odc_ip2003_ta/html/odc_inArch.asp?frame=true

http://msdn.microsoft.com/library/en-us/odc_ip2003_ta/html/OfficeInfoPathWebServ
iceASPNET.asp?frame=true

http://msdn.microsoft.com/library/en-us/odc_ip2003_ta/html/odc_ipinfopathdecisio
ntree.asp?frame=true

http://msdn.microsoft.com/office/understanding/infopath/default.aspx

---
S.Y.M. Wong-A-Ton