Use the dedicated offline installer for XP and Vista provided by AVG support to ensure compatibility.

Since the offline PC cannot connect to the update servers, you may need to periodically download the manual definition update files (often labeled as vps ) from the AVG website and apply them within the program interface.

Download the .exe file on a modern machine, move it to a USB drive, and then run it on the Windows XP computer.

Using an offline installer is the most reliable method for machines without web access or those behind restrictive firewalls. Because the main AVG website often redirects to the latest (incompatible) version, you must use specific legacy links.