I hesitate to tell you how I solved my problem since it took me so long to figure out an in retrospect was so obvious. Perhaps you have the same problem.
I am developing a blog and wanted to do it on my laptop first before signing up a server. So I followed the directions on the wp site and downloaded not only wordpress v2.6.3 (to C:\wordpress), but also xampplite which runs MySql and Apache. I downloaded that software to C:\xampplite.
My error was that I mistakenly thought I only had one version of wordpress on my machine and that it was at C:\wordpress\etc... So I made all my changes to the templates in that directory structure.
However, it turns out when you download xampplite you also download wordpress to something like C:\xampplite\htdocs\wordpress\etc. And this is where the wordpress software runs from. So for a full weekend I was making changes to the wrong styles.css file and it wasn't until 3 days later it dawned on me to do a file search on my whole C drive to find all versions of kubrick_header.
Hope this helps though I suspect you've already checked this.