Need to know how to effectively rip, edit and burn

I want to rip sermons off of my dvd+rws that i store them on then edit them in my computer then burn them back on dvd+r’s but seems to be almost impossible unless i have conversion software to go from iso to avi or mpeg can anyone help me with this.
I have dvd decrypter, pinnacle 9, my dvd, and movie maker just so you know.

If i need something else then i am happy to get it if it will work and make this an easy transition.

Thanks in advance

What format are your sermons on DVD-RW stored in?

most likely you will dvd authoring software.