I am a small company that wants to get into the backup/restore business from my house for small Mom and Pop companies. I want to be able to backup company's data to my fileserver and I want to use only Open Source software for Windows. The criteria's that I need to meet are as follows:

1. I want to have the User be able to web into their information at any time.
2. I need good security so other companies won't see the competitor's data.
3. A good Open Source software that will be easy to use in a disaster recovery situation
4. Would I use just FTP software in conjunction with an Open Source backup and Recovery program or something more elaborate.