Customizing security settings in Internet Explorer 7
To find the security settings in IE 7:
First, open the menu Options and then the entry Internet options.
Under the Security tab, select Internet.
By default, the security level is set to medium (preset). This setting is a good compromise between security and ease of use. But if you want to be on the safe side, set the security level to "high".
Internet Explorer allows users to fine-tune the settings via the icon "Custom level". Click on this button to open a list of more than 40 detailed settings. If you edit them, make sure that the settings for ActiveX and Active Scripting are not too lax because these techniques are commonly exploited in attacks.
Excursus: Internet Explorer's zones