Here is an example to allow File Uploads upto 2 GB. You may also have to consider Max Execution Time.
PHP4:
<IfModule mod_php4.c>
php_value upload_max_filesize 2G
php_value post_max_size 2G
</IfModule>
PHP5:
<IfModule mod_php5.c>
php_value upload_max_filesize 2G
php_value post_max_size 2G
</IfModule>
