How do you use disk utility to burn a bootable .iso dvd?

Anybody have a clue on how you use disk utility to burn a .iso bootable dvd disk?

I'm trying to install windows 7 rc into virtual box in OS X 10.5.7 and cannot figure out how to do this. I've already installed the windows 7 beta in virtual box and was able to make a bootable dvd disk with the .iso file on it but have no clue how I did this.

I've been searching the web but most tips are for older version of OS X.

Thanks to anybody who answers.