What do I need to do to protect myself from Viruses?

There are several actions you should take:

Purchase up-to-date Antivirus Software. My current favorite is Norton Antivirus. New Antivirus programs have better technology for scanning email as it comes in, updating themselves easily, and finding virus like activity, even if the virus has not yet been recorded.
Keep your Antivirus Software current by downloading Virus Profiles and program updates on a Weekly basis. If you do not keep your Antivirus software up to date, it will quickly become useless. New viruses are released on a daily basis. These updates give you protection against new viruses as they are discovered. With the increasing use of the Internet, viruses spread much more quickly. It is not uncommon to come across a virus within two weeks of it being discovered.
Download and install all security patches for your Operating System. If you are using Windows 98 or newer, Microsoft has an update utility available at http://windowsupdate.microsoft.com. Many viruses will exploit holes in windows, and the common windows email software (Outlook, and Outlook Express). Installing these patches will protect you against many of the known security flaws in Windows.
Use common sense when handling incoming email. Do not open any email attachments that you are not expecting. Email attachments ending in: .scr, .bat, .pif, .exe, .com, .js, and .jhtml, are very often viruses. Do not open files with these extensions, unless you are absolutely sure that you know what you are doing.