Don't just install on autopilot. Like many programs, AVG Anti-Virus-Free-Edition bundles on add-ons that round out the program. Choosing the custom installation gives you the chance to see what's being offered, and a chance to decline individual features.
Along with the basic antivirus and antispyware engines are extra plug-ins to scan e-mail messages and attachments for threats, and an additional browser toolbar. If you're interested in just the basic shield, the custom install screen is the place to uncheck the extra boxes.
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