File Upload Size Limits

I am running PHP 4.0pl1 with Apache 1.3.14 on RedHat Linux 7.1. I am trying to do a file upload from the users PC to my web server. If I do a small file, the transfer goes fine. If I do a large file (> 50 MB), the transfer fails saying either the file was not available for reading or my script just bombs out. I need to be able to have people upload large files. I have changed the setting in php.ini to upload_max_filesize = 100M. Do I also need to change the following entries in php.ini? max_execution_time = 60 memory_limit = 8M Is this an apache limit? I'm not sure what to do with this as I really need to be able to transfer large files.