Even with the better security of Firefox compared with Internet Explorer, McAfee Site Advisor is a good way to sort the good from the bad online.

Once installed it appears as small area of text in the bottom right hand corner of the browser window. This changes colour depending on the website. Green signifies a website that can be trusted, yellow a site that might send lots of emails or red for sites that are known to send spam or bundle adware into downloads.

Clicking on this text gives the option to read more information about the site. This includes the number of emails received after registration and whether the website links to any suspicious sites. Downloads hosted on the site are also checked.

Most websites are tested by computers at McAfee but it is possible to submit a user report if you feel that a website has been the cause of spam or adware.

In this case the website will be looked at by a member of the McAfee team, rather than relying on automatic checking. The site owner can also leave a message responding to the rating.