Ubuntu Servers :: Backing Up Server Before Updating?

I've been running my little server at home for a few months now, and I've noticed that Webmin has detected that I'm in need of over 100 updates. I'm a bit scared to run the updates because everything is working just fine right now, but a part of me still wants to run some of the updates.Now I know backing up the server would be a good idea to do before this happens. This server is a media server with videos, music and pictures taking up the majority of the hard drive space on the server. I just have one partition on the server, outside of the swap partition. I would like to back up everything on the server except the videos, music, and pictures, because if even an update messes with the server, I could always retrieve those, and the external hard drive I'm going to back up to wont be big enough to hold everything anyways.

if I were to backup up everything except for those directories that hold my videos, music, and pictures, and something were to go wrong, if I were to restore all of those, would I then be back to the state my system was at when I backed up? I've never done a back up and restore in a linux environment before. I just want to make sure that just doing that will be enough, because the last thing I want to do is hose my server after taking several weeks to get it to the working state that its at.