How to allow user to Upload files?

I’m working on a site for a Printing company and they want to allow their customers the ability to upload their artwork. I’m not sure the best way to do this. It’s running on IIS 6 and it’s hosted inhouse so sending it to an FTP client is an option but it might be nice to have it drop as an email attachment from the site so space on the server isn’t wasted.
I’ve never added this functionality to a website before so I’m looking for suggestions from the seasoned pro’s out there.
Thanks!