antivirus malware

My wife recently "accidentally" installed and paid for an antivirus software called "Win Antivirus 2006 Pro". I say accidentally as a "trial" version of the software installs itself from visiting some rogue websites, then it seems to cause a lot of junk popups which it promptly fixes once you buy the product.

Apart from the aggressive/dishonest sales tactics, which don't exactly give me a good impression of the product! it's unclear to me if this software is any good, or if it's more spyware/malware as many websites seem to suggest.
What does seem very clear from the websites I visited is that this software is very difficult to uninstall **cleanly**.

In any case I'd recommend staying well away from software which (very cleverly) pops up suggesting you buy it.