Seriously? In windows land it is the norm to always run as an administrator? Over here in Ubuntu and Apple land I never run as an admin, although I'm not sure if that is normal in Apple land.
'Out of the box' Windows doesn't insist on having a user account so many (or most) people either use an admin account or give themselves admin rights. There is no su equivalent command (well, run as admin but not quite the same) and the majority of users don't realise the impact / risk of being an administrator.
Tadpole - sorry to disagree but it's not OK to run as admin all the time no matter how experienced you are. If malicious code can be executed from local drive, USB, email, Javascript, webpage, etc and you have administrator rights, you cannot stop it doing what it wants - a firewall will reduce the risk of malicious traffic and AV can stop an infection but only if it can be identified. Even heuristic scanners are limited in what they can achieve.
Backups are important and everyone should have at least 2 copies of their data in different place and on different media (i.e. NAS box & dropbox, DVD & magnetic tape). However, backups only help you recover in the event of a failure (malware based or not) and as the Doctor says, prevention is better than a cure.
BTW, if anyone wants a Dropbox account, please use
this link as it gives both me & you an additional 250Mb of free storage (in addition to the basic 2Gb).