The bare minimum to consider to protect your computer from being hijacked by the dudes in the black hats.
Using WIndows? Make sure your Windows computer remains up to date on security patches from Microsoft. Open Internet Explorer, visit http://update.microsoft.com , and let it scan your PC for missing updates. Install any security patches it says you need. Windows users also can configure their PCs to automatically download patches as Microsoft makes new ones available.
This has been said so many times, we are all bored with it. BUT DO IT ANY WAY.
Use antivirus and firewall software. Without these you mat as well just give your PC away. You can find detailed, step by step instructions over in the “Permanent Pages at your right called “Stopping Malware“
Use a decent browser (here’s a hint IE isn’t on the short list) Try Firefox or Opera. Lets at least make the bad guys work for it.
The bottom line is be sceptical when downloading or opening stuff in your email. E-mail and IM networks are the most popular ways to spread viruses and worms, and many will appear to have been sent from someone you know.
I know all this is obvious but it’s been a bad week for it.