hibernate ejb3+Tomcat+Openejb or Spring+hibernate for an exsiting GWT2 project

I used GWT2+DAO pattern for my apps and it's work correctly. Now my BD as grown a lot and i want to manage it more easier. So I want to use an ORM.What i want to do is to keep my first DAO implementation and use hibernate for my new classes. But I read a lot on internet and I'm very confused about the way to deal with this. 1-which solution between hibernate ejb3+Tomcat+Openejb and Spring+hibernate could be better for me? 2-also which one could be the fastest? 3- Should I change all my dao to use hibernate methods or should I use the both? NB: I'm just started to read spring doc, but I have already read hibernate doc. thanks.