msxml problems

I'm working on a project using xml via the IXMLDOMDocument interface and I'm running into a problem with getElementsByTagName() method. It should take in a BSTR and spit back a collection of xml element pointers, but it looks like I'm getting back garbage every time.

I got started from this example:

http://codeguru.earthweb.com/xml/XMLDOMFromVC.html

it uses the msxml.dll. All of the info on MSDN uses msxml2.dll or higher. I've installed msxml4.dll and made some changes to my code, which compiles, but immediately crashes with a popup that says "class not registered". Any ideas on what I can try next?