tracyberna:
Fatal error: Call to undefined function libxml_use_internal_errors() in /netapp/whnas-silo1-node1/s8/s8/01296/www.mysite.com/webdocs/blog/wp-content/plugins/wordpress-importer/parsers.php on line 59.
that's occuring due to you using a older version of PHP, It seems the latest WordPress importer includes a PHP 5.1 function whereas, WordPress 3.1 only requires PHP ~4.3. (The alternative, is that XML parsing (libxml) is disabled on your PHP installation, which is possible)
WordPress 3.2 due to be released shortly requires PHP 5.2.4, so you may find the server your client is on, is incompatible with the latest version of WordPress anyway, fixing that will allow the importer to work correctly..
The memory limits mentioned for whitescreen errors are not the upload size, nor the diskspace, it's related to how much RAM memory WordPress can consume, some hosts limit you to using a small amount of memory which renders WordPress unable to read the import files properly.
To attempt to work around Memory limits with the importer, you can attempt increasing the memory limit of WordPress, to do so, insert this after the opening <?php of the wp-config.php file:
define('WP_MEMORY_LIMIT', '64M'); - You should only need that while attempting to import the site. Alternatively, Wait for 3.2 which is due to be released shortly, which should attempt to bump that for you automatically.