Viruses, Trojans and worms have been replaced by spyware and adware as the security-breaching buzzwords that play on the minds of home PC users.

It’s a multi-million dollar business, we’re told, to develop cunning apps that break through your PC’s defences so they can sit quietly on your system while surreptitiously sending out your personal details. Certainly, we’re seeing more and more of these threats and in the same way that antivirus firms cash in on your fears, antispyware firms are now benefiting from the public hysteria. They tell you that if you don’t have an antispyware utility, you’re signing a death warrant for your PC.

But who watches the watchmen? A representative of a security firm told me last week that adware developers are coming up with increasingly underhand ways to bypass your defences, ultimately seeking partnerships with the companies that pledge to protect you.

The representative’s company had been approached by an adware developer that wanted to pay to use its antispyware technology so that its marketing or malware code could pass uninhibited on to PCs. That particular piece of spyware could then delete the other spyware residing on your system in a ploy to scupper the competition (too many instances and your PC will slow to a crawl) while allowing it to successfully go about its business.

It’s a calculating strategy that could ensure your PC continues to operate apparently as normal, leaving you with no idea that your protected system is under threat. And although the antispyware firm I spoke to said it would never consider sleeping with the enemy - the stakes are too high for the best-known brands to play along with this - it makes you wonder whether some might be tempted.