If you were able to take a look at the Microsoft Calculator accessory running on, say, Microsoft Windows 3.1 and then take a look at the Calculator on XP or Vista, the most striking thing would be how little it has changed over the years (over a decade). Microsoft does have a free PowerToy, however, that you might want to use instead of the included Calculator.

Microsoft Calculator Plus

Since it requires a Genuine Advantage check before you are allowed to download it, you should fire up Internet Explorer for the task. GA doesn't like Firefox.

Calculator Plus has three views: Standard, Scientific, and Conversion. I have the Scientific calculator showing in the image above. One nice aesthetic touch is the transparency effect seen when focus shifts away from Calculator Plus to some other window.