What are my options?

Hi All:

We have been with the SAP applications over the past 3 years, running currently on Enterprise. We have implemented MM module, basically for our purchasing activities (we are not a manufacturing-sales centric org).

We now wish to be able to enter and review purchase orders on an external (oracle based software) system and link the same to the SAP R/3 system.

Would you please enlighten me with the available options, including add-on packages and upgrading the R/3?

Thank you in anticipation.