Yes you need one of those drives with rawdump to backup an original.
I am assuming you have got the .ioo file because you have a FAT32 file system on your PC and it has split the DVD into two files.
Normally you get an .ioo file, and .ioi file and a .mds file if it has done this.
Just open the .mds file in imgburn, because this is the cue sheet for the other files, and burn to a blank dvd. The .mds cue sheet should combine the two files and burn those to the DVD