what is in a theme can vary greatly. How many files and stylesheets they have depends on how complex they are, or how much they have been modified. More important, the more files they have the more control you have over the look/layout.
I don't mean to be rude, but there are so many better looking, more professional themes than the one you posted.
Here's a good list:
http://www.smashingmagazine.com/2008...dpress-themes/
which has even more links at the bottom of the post to other free themes.