I'm using CoreFTP limited edition, free version of the program for my daily uploading website contents. I've noticed in many occasion that I'm having problem uploading big files. So I decided to try Filezilla FTP client.
The filezilla FTP client is another open-source that you can use to upload or download files. Not just a client, the Filezilla offer a server version for Windows to make files available for others to download. As of this date, they only provide FileZilla Server for Windows only.
I've installed and tested it, easy setup and fast to upload files to my server. Check it out and let me know if you have questions.