Then I figured out I could manually type in the HTML code to center a graphic in Firefox and that worked fine; it's just the shotcut key in Blogger that wouldn't center an object if using Firefox. (It did center text though.)
Having gotten my last hurdle behind me, I was all ready to ditch IE7. Then two things happened. A company where I may be doing some consulting work has set me up with an email address but I have to access it through Microsoft Office Outlook Web Access which, according to the IT guy, only works with Internet Explorer, not Firefox. And suddenly the horizonal scroll bar disappeared from Firefox when I'm in the Blogger layout mode of my blog template.
I can't make changes to my blog layout without the horizonal scroll bar and apparently this is a common problem with Firefox according to some Google searches I've done, although most people seem to report the vertical scroll bar has disappeared.
To cut a long story short (too late for that), I have downloaded the Opera browser and will try a test post with a graphic and see how it looks. However, already I see a problem: the graphic in the post just below this one (the 67 countries thingey) is now left-justified when viewed with Opera, while all my other graphics are centered.
Can we tell I'm having fun?
Cool... now it may be time for a D.I.V.O.R.C.E. from Firefox.
How does it look from your end?