When you say Google, are you referring to Google Chrome? If so, then what you're looking for is the uninstall routine for Chrome, which should not have anything to do with Firefox at all, no matter which one of the two browsers is the default browser. So clicking Firefox to manipulate Chrome would definitely be the wrong path. Under regular circumstances, you should actually have the choice which one you want to have designated your default browser, but still be able to keep both installed just in case, if that's what you actually wanted when you installed Chrome. There are several extensive step-by-step instructions on the Internet on how to set your default browser on Windows XP. In short, you should be looking for the dialogue named "Set Program Access and Defaults" which should be accessible either directly from the Start Menu or by opening the Control Panel and then opening "Add or Remove Programs", where you can basically do both things, uninstall Chrome from the list of installed programs, and then set Firefox as your default browser by picking the "Custom" option and adding it manually. Firefox may even be able to integrate itself as the default browser from its own Options/Settings dialogue, so you could also give that a try.