FYI, JS is really easy once you read a few tutorials on it. I used to be just like you - HTML/PHP genius, but slow with JS. Tutorials and some books helped; this was very helpful!
I don't remember reading the article (although I'm sure I did - I've read so much about AJAX - look at my title), but I'm assuming that the drop-down selector is using a function onchange? Like "<select onchange='function()'>"? Then all you have to do is take the function, and make the hyperlink do this: "<a href='javascript:function()'>text</a>".
If you're having trouble specifically with AJAX, let me know, it's my brainchild!!
Edit: probably shouldn't have said that. didn't sound right 😃