ergophobe - 10:48 pm on Jul 31, 2010 (gmt 0)
loading a style.css file into my themes/default folder
I meant loading it into your browser. That is, typing into your browser bar the direct address of where the CSS file is supposed to be and seeing if it loads in your browser or gives you some type of error.
When you open a page that should be managed by Wordpress and then look at the source, where is it looking for the stylesheet? Does that correspond with where the stylesheet for that theme is located?
Questions like these will enable you to figure out where in the process things are going wrong.