What is Best Org. Structure for Medium Sized IT Company

We are a 60 person IT company with a very high visibility and impact in financial services industry. We are experiencing growing pains: we are transforming from a small company where everyone was wearing multiple hats to a company that needs better organization and process if we are to scale. My question is what an optimal structure for our IT department should be.

Currently we just have Application Development and IT Operations. Neither department has strong long-term engineering effort; we are just working on ad-hoc feature enhancements and putting out fires. I want to change that. I want to make sure we have strong engineering department both our application development side and systems side. I want people thinking about how we can get to the next level from our server and networking set-up to our software architecture. I want the same thought process in our DBA department. I want QA being more independent and proactive. Out systems seem to be in need of serious tuning, re-architecture, comprehensive monitoring system and our application development has holes in the SDLC. The good thing is I have the mandate from the CEO to make things better, but I would like some guidance and best practices on how to best organize our department, and I am willing to bring in some strong technical and engineering talent.

I would appreciate the input from the collective wisdom of HN.

Thank you.