When Reomel Lamores (aka ‘Spyder') unleashed the Love Bug virus on to an unsuspecting world nine years ago, it created havoc across the globe. In a single day I-LOVE-YOU infected 10 percent of all PCs connected to the web, causing about $5.5bn (£3.6bn) in damage.

What it didn't do was make Mr Lamores' life any better - or make him any richer. In those days, hackers worked only for fame, although many reformed script kiddies have since gone on to big things in legitimate coding.

Fast-forward to 2009 and the world of cybercrime is a very different one. Virtually all the estimated 1.66 million new threats released into the wild in 2008 were written and propagated with one thought in mind: money.

Malware is increasing exponentially, but nobody does it for fun, and hackers no longer work alone. More than 90 percent of attacks in 2008 were instigated by organised crime.

Getting into your PC is big business, then. In fact, it's almost as big as the industry that strives to protect it. So when a ‘big name' virus starts to make headlines and starts insinuating itself on to significant numbers of PCs, it's time to sit up and take note. That's exactly the case with the latest example, Conficker (aka Downadup).

Conficker was released in October and spread like wildfire, exploiting a network service vulnerability in all versions of Windows. Such was its virulence, it was able to infect more than nine million PCs by January 2009.

Its purpose was to send spam and generate revenue via antivirus scareware. It was designed to create a problem and then offer to ‘solve it' for a small fee.

Thankfully, preventing a Conficker infection is easy. Our tutorial shows you just how easy.

But first, we address that rarity of modern malware: one written just for fun. Mikeyy, a worm that attacks Twitter accounts and sends spam Tweets, was written by 17-year-old Michael Mooney because he was bored and wanted to promote his site.

The easiest way not to be affected by Mikeyy is not to use Twitter. If that's not an option for you, read on.

Beat Mikeyy the Twitter worm

1. Twitter users should never click any links in messages containing the words ‘Mikeyy' or ‘Stalkdaily'. This may sound obvious but, if a friend's account is infected, you could receive messages from someone you trust offering advice on avoiding Mikeyy, with a link to a ‘useful article'.

Removing Twitter's Mikeyy worm: step 1

2. It's a good idea to use third-party Twitter desktop clients such as Twhirl or TweetDeck - both work for PC and Mac - and avoid using the web-based version of Twitter. This is especially true for viewing user profiles, because this is where the attack generally seems to originate.

Removing Twitter's Mikeyy worm: step 2