Backup software suggestions

I need suggestions on backing up one XP and two Windows 7 and one OS X Lion systems over the network to a 2008 Server. I’d prefer free or low cost solutions where you can juts set it and forget it.

My backup target is a removable HDD on the 2008 server.

Given your mixed systems, I would take a look at CrashPlan. I’ve been using it for a while now and it exceeds my needs in a mixed environment (3 windows and 3 linux systems). The software can be configured for multiple backup destinations on any given system (local directory, remote directory, CP’s servers (with paid subscription), even a friend’s computer running CP). All backups are encrypted and you hold the key. Reports can be automatically emailed on a schedule detailing the progress made on each system. I really can’t recommend it enough.