I have no choice but to use the Microsoft OS. That said, MS has quite obviously engaged in planned obsolescence in their software products for several years now. It's their only available strategy for maintaining sales volume. That is why newer versions of Microsoft Office create files that can't be opened by older versions of the software -- unless you convert the files, free of charge, on an independent website.
If you're using a Microsoft OS and IE, then you should always use the newest version of the browser that is available. Upgrading can also relieve you of some of the more sinister
BHO's (No... Not the President -- Browser Helper Objects) that you may have accumulated while surfing with the older version.
In general, I would recommend avoiding third party "toolbars", weather bugs and such. They aren't offered to enhance your browsing experience. They are offered by these third-party vendors as a means to abuse naive web surfers. Most folks voluntarily install mal-ware on their computers when they agree to accept these "free" apps.