CD Writer vs DVD Writer or Combo

I'm trying to help an email Friend with a new computer purchase with the things she thinks she wants.

I don't know the answers so I'm seeking advice and answers from you people that know.

She is a Genealogist, hope I got that right, that works out of her home. She stores mountains of information and has been doing it on CD-RW as she visits the information and make changes a lot. She's looking for another option as CD don't hold all the info she sometimes has on a family.

She has picked a Dell machine but doesn't know what to include.

I have heard about the new DVD combo writers that read and write all formats, DVD-R, +R, -RW, +RW, as well as CD-R & CD-RW. Am I correct with this? Do they read and write to the original disk that was made as CD-RW? I'm recommending the DVD Writer as it will hold several GB as opposed to CD of 800 MB or less.

I don't want to steer her wrong. Information and advice will be appreciated. I suppose that I could look up all this but figure the experts are on the Forum!!!

 

Thank you Sir.