The recent Red Hat email scam highlighted one thing, with the growth in the popularity of Linux these type of threats may become part of everyday life. As this article correctly points out the increasing threats in Linux has more to do with the user base changing i.e. an increasing number of new users, Linux is inherently more secure than Windows but that means little if users do not implement basic security measures when it comes to their Linux box.
The key to security is being aware of the threat.

I am by no means a security expert when it comes to Linux but here are a few points to get you started

Most of the mainstream distros have a security mailing list, subscribe to it. Emails sent from these lists are usually signed with a GPG key ensure it’s authentic before following any instructions given.

Use a firewall, distros like Mandrake and Suse have built in firewalls. You can learn more about firewalls and Linux here.

Never use the root account as your regular account. Create a separate account if the install didn’t create one for you and then use su for tasks that require root privileges.

Rootkits remain the most serious threat to your Linux box. Download Chkrootkit or my personal favorite Rootkithunter and scan your system regularly.

Until next time be safe :-)