A school recently contacted me when a teacher had a complete data loss after a work order was placed to fix a problem. Unfortunately, through no fault of the teacher, other than she had not herself taken explicit action to back up, all of her work was lost.
The district does provide some space on servers to back up to. You do have to take action, however, to use it. I'm attaching a PDF called Backup to help you with this. Please consider taking action now before disaster strikes!
Finally, if at some point you are forced to migrate to a Windows computer, much of your data will be fine. The content in iLife applications is, for the most part, not. Before that happens, go into your iLife applications and export into formats readable by Windows applications. From iMovie, export to QuickTime. From GarageBand, export to iTunes (you'll have to either move the library yourself or insist that it be moved for you). Your pictures in iPhoto will be ok, but your slideshows should be exported to QuickTime. Just be sure to copy the iPhoto library. Finish up any iDVD projects and burn them. Your iWeb sites will be difficult to continue to edit, but copy your content into text files at least.
As always, contact one of us if you need some help with these tasks.