PHP - Memory_limit

Hello.

My script is set to upload files upto 5GB large.

For that script I've currently set memory_limit to 5GB. Is it alright?

I mean what is the ideal value (for large upload scripts)

If you feel, 5GB is large. I can make script to upload 2GB files and set memory_limit accordingly.

Also, max_execution_time has been set by me to 86400 currently. Assuming, on a 500Kbps broadband, it would require upto 24 hours to upload a 3-5GB file.

Please suggest.

Thank you.