Finding out what user Apache is running as?

I want to secure a file upload directory on my server as described beautifully here, but I have one problem before I can follow these instructions. I don't know what user Apache is running as.

I've found a suggestion that you can look in httpd.conf and there will be a "User" line, but there is no such line in my httpd.conf file, so I guess Apache is running as the default user. I can't find out what that is, though.

So, my question is (are):

• how do I find out what the default
  user is


• do I need to change the default user


• if the answer is yes and I change the
  default user by editing httpd.conf,
  is it likely to screw anything up?

Thanks!