I get reminders quite often about Firefox 8.1 to replace 3.6. I have several computers with Windows XP SP3 and one with Windows 7. When Firefox 6 became available, there was a Mozilla-supplied program that determined that too many of my installed applications were incompatible with Firefox 6, so I did not install it. There seems to be no similar utility for Firefox 8. How do I determine how much trouble Firefox 8 is going to cause me before I install it? Most of the computers have similar programs installed (some "old" such as MS Office 2003) in addition to the identical operating systems.