I wasn't able to find any information on this (on my level), so I just ask:
Due to old hardware, I can't move on to a newer version of Ubuntu (e.g. Jaunty was the last one where the v4l1-fix worked; and I got other problems like 10.04 stopping at ~80% setup process/different hardware conflicts, which I won't be able to solve any time soon/$).
Ok, I hope this not to be offensive (I mean, just an exotic minority problem), but provided one would be willing to -> what parts of the system should be updated manually, in order to stay safe, and where does one find reliable security bulletines/mailing lists so not to damage something? As far as I can see, it should be safe to keep the kernel patched + webbrowser (Opera), video chat software (Ekiga/Zfone), FTP (NcFTPsyncput) and firewall (ufw) up to date, provided one doesn't exchange office files (except Google Docs cloud viewer), nor e.g. has an email client.
But I'm not experienced, and work in a field where it would be a desaster to find oneself hacked...