jmustac on "ftp file upload via a webform?"

I have a Drupal website that I need to allow customers to upload large files (over 100MB each). I have tried PHP webforms but its too slow and just doesnt work.
I dont want to bother my customers with running an ftp client program.
is there a way of running an ftp client from within a web page?
Can i use the power of ftp within a webform?
There seem to be small apps you can buy to do file upload but I'd prefer to figure this out myself (and with your help :-)
thanks