I just read and the NVU site that one should (NOT) use Capital letters within their file names, But did not specify WHY. Could this be because visitors and internet users search with just uncapped letters and the search engines distinguish the two, therefore if one used capitals in their file names visitors would'nt be able to find you even though the typed in the same phrases.

I cant think of any other reasons unless search engines rate those sites poorly for i guess screaming out like that.

If my first guess is correct then i've been making a pretty crucial mistake.