I have shared large files directly from my laptop. I have IIS installed and just opened my firewall and gave them the password. They connect and download it. For a file that large, depending on the connection speed, it could take a while to complete the transfer.
Unless you your computer is on all the time or you have a machine dedicated for this purpose you may have to coordinate when they can connect. There are several FTP server softwares available if you have Win98/ME or XP Home (no IIS).
Having the connection speed is the biggest issue. Cox cable can be used but the upload speed is limited and standard port numbers are often blocked just to prevent people from doing this. A DSL connection usually has less restriction, even a dialup connection will work but it would probably take a day and a half to transfer the file size you are talking about.
Also keep in mind allowing access to you computer in this way opens it to various attacks. Keeping up with updates and configuring security settings is highly recommended.
Idealy a hosted webspace with sufficent storage is the the best solution if not the cheapest.