Ajax Web Service XML Load to DropDownList via Javascript

I need to call a Web Service which returns an XML document via Javascript. I then need to then load the XML into a DropDownList, again, Via Javascript.

I'm displaying the dropdown in an Ajax ModalPopup control, and the dropdown is sorted based on the user's selection of a radion button (ex. either sort by name or id). The Web Service will list users either by ID or Name (ordered respectively) based on the radio button selected by the user.

Because I'm doing this in an Ajax ModalPopup, I have to avoid postback (at least my understanding of the ModalPopup control).

I'm getting familar with calling a web service via Javascript. I was hoping there was an easy way to populate a dropdown via Javascript using an XML document.

Any advise greatly appreciated.
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