ISO Recorder is a cool too that enables you to copy a CD/DVD to an ISO file, as well as to burn a CD/DVD from an ISO file. The author has now created a version for Vista, which is now available from http://isorecorder.alexfeinman.com/vista.htm.
This is an early build with its share of issues, but it can burn DVD images. There are both 32 and 64-bit builds.
And thanks to Mark Allen for finding the error in the earlier version of this post!