Trouble with sidebar.php

I’m trying to play with the sort order of my Links, even going so far as to implement the “MyLinkOrder” plugin. Problem is, no matter what I do to my sidebar.php, it has no effect on the appearance of the links in the sidebar. I started getting suspicious when I dumped a bunch of nonsense right in the middle and it had no discernable effect. I should mention that I have also implemented Sidebar Widgets.

So I deleted sidebar.php, and what do ya know? No bloody effect. Everything over in my sidebar appears just happy as you please. So that leads to my question:

If the blog isn’t determining the format of the sidebar from my theme’s sidebar.php, where is it getting it from? Is there a “default” sidebar.php someplace? What tells a given page to build its sidebar using that particular file?