ESBCalc is a Freeware Windows Scientific Calculator with Infix Notation, Brackets, Scientific Functions, Memory, Optional Paper Trail, Result History List, Customisation of the Colours and Fonts used, Customisation of the Hints, and more. Functions include Trigonometric, Hyperbolic, Logarithmic - Base 10, Base 2 and Natural - and many more. Now includes Prefix Function support so that Log (1.3) can be entered as log 1.3 rather than as 1.3 log which is the default behaviour.
Looks best with Windows XP in 800x600 (or better) and 32-bit colour.