I have a network of about 30 Windows PCs.
What good free software is available that will automatically (scheduled) make backups (not whole HDD but only certain folders) for these PCs and save on a remote server which will be used only for storing the backups? Preferably the server will run Linux and the backups will be stored via FTP, where each PC will have its own FTP account.
I've had pretty good experience with Cobian Backup. Runs as a service, can backup to compressed (Zip & 7Zip) and move to an off-site (FTP et al) location. I haven't tried to deploy it to several computers at once, but every other experience I've had with it has been superb.
Also, as Alex notes, it can send e-mail notification upon completion/failure, and I believe can be remotely admin'd.
Give BackupPC a try.
It's extremely space-efficient; can handle many types of connections; has a good web interface; needs no client-software; etc.
It's not push but pull-style backup, reducing the things your clients can screw up.
All-in-all we're very pleased with it.
If they're Windows XP-based PCs, you can use the built-in NTBACKUP and fire it off from "Scheduled Tasks". This is a good "no third-party software" solution, and catches NTFS ACLs. You can backup to a file and then move it with FTP.
If you're not stuck with FTP, and perhaps concerned about bandwidth usage you could use one of the various rsync ports and an rsync server on the Linux machine. Cwrsync (http://www.itefix.no/cwrsync/) is a decent one, but beware that it doesn't replicate NTFS ACLs.
You could knock something together with, like, ZIP and a scheduled task to FTP the ZIP file, but if you're going to do that you might as well use NTBACKUP.
I can recommend SyncBack. Even the free version has an impressive feature list.
Does it have to be FTP?
If it could be Samba, then NTBackup would do it easily.
I would recommend rsync+ssh for almost all basic file backups.
There are a number of builds available for Windows environment, the one I use being that found in the CygWin distribution: http://www.cygwin.com/
For a lighter client install you might try http://www.itefix.no/i2/cwrsync
Check out FBackup, this should be exactly what you are looking for.
Have a look at Bacula - our hosting company is using it to backup our servers and don't seem to have any trouble.
Amanda is another free solution for this kind of situation. It has a windows client which supports VSS.
Bacula seems to have better support for disk to disk and file retention control though.
I prefer it to Cobian as it has more flexible backup schedules, bandwidth management, and restore options.
Even know everyone has added their own version, I have used Owncloud. Run's as a linux server and requires a client. Sync's the folder, very useful.
There is a windows client, mac and linux. It runs under apache and stores the date in the public_html location. Simples!