Urllib vs. FireFox

[Rex]

Right. If you want to get the same results with your Python script
that you did with Firefox, you can modify the browser headers in your
code.

Here's an example with urllib2:
http://vsbabu.org/mt/archives/2003/05/27/urllib2_setting_http_headers.html

By the way, if you're doing non-trivial web scraping, the mechanize
module might make your work much easier. You can install it with
easy_install.
http://wwwsearch.sourceforge.net/mechanize/