They are using this as a vector to install Chrome.
That annoys some people, but at least the people most likely to be running IE 6 or 7 at home are also the ones most likely to remain co-opted-in to a Chrome download.
I have my doubts that bundling a browser with other software will really convert those that don't know what a browser is.
They go online by clicking the blue 'e' icon on their desktop or start menu, as that's what they've always done. Adding another browser or changing the default browser doesn't change this behavior, and IE will ask the user to make it the default again as soon as they do.
I find the forced "Google Update" install more annoying.
Plus, the uninstall note for Google Update points out that if you want to remove it, you must first remove all Google software, otherwise the Updater will be reinstalled within hours.
That annoys some people, but at least the people most likely to be running IE 6 or 7 at home are also the ones most likely to remain co-opted-in to a Chrome download.