Opera is a complete browser...it is even more 'compliant' with standards than I.E. and FF....which means some stuff is written so that NON-compliant is required, and Opera doesn't work as well as FF..(I have FF for those occasions)(some of those are things like secure bank log-ins...etc.) Opera isn't set up for myriads of add-ons, like FF, so you need to accept that it doesn't do as many 'tricks'...but it does what it does very well.

K-Meleon is smaller, faster, but is not as 'easily' configurable as other browsers. It works fine right 'out of the box' and is being slowly, but constantly, improved. Many folks use it as their default.

Oh...and "Old Version" has many, many older versions of other programs.