Latest version of the camera driver is 126.96.36.199 and it was released on 2009/10/23. You can download it from the Acer Support website.
Please visit the website and follow this path to get to the downloads section: Netbook > Aspire > Aspire 4220. After you've reached the page, make sure to select the right version of Windows that is currently installed in your computer.
It's OK if you want to update using overwriting files, but it's better to completely uninstall the version on your computer and then perform the installation.