White screen of death when uploading a file attachment
mod_fcgid have to do with FastCGI.

There are actually a few PHP settings you may need to investigate and modify.

Reference: Increase upload size in your php.ini

In short though, you will need to up your upload_max_filesize as well as your post_max_size

Also, I would recommend watching your /var/log/apache2/error.log (Default location in Ubuntu 10.4) while debugging.  Generally running sudo tail -f /var/log/apache2/error.log will show you 'white screen' errors in real time.