Hi Steve,
Default folders of what you need :
C:\Program Files (x86)\SAP\SAP Business One SDK -> Samples and Help
C:\Program Files (x86)\SAP\SAP Business One DI API -> This is what you are really looking for
If you can't find it on the server, it might not be installed.
Note that SAP can still function without the 2 folders, and installation is optional.
The DLL you are looking for is SAPbobsCOMxx.dll (xx denotes the version of SAP your client is using)
under each subfolder of the 'SAP Business One DI API' folder.
Install them first.
If you are looking to update SAP using XML/XSLT, you should be looking for B1if.
The default folder is :
C:\Program Files (x86)\SAP\SAP Business One Integration
Again, this is an optional install, your client may not have installed it.
With this, you do not need to explicitly use the DLL, it is wrapped inside this service.
Regards
Edy