More scaling examples (ignore the filenames). View 1:1 at a 1080p monitor.
Here's C&C, which is a worst case scenario if you want clean scaling with black bars since it doesn't use square pixels and MUST be stretched on a modern display. nearest.png is nearest filtering and while it looks very sharp, scaling artifacts are obvious. Text is the most obvious way to see it, look how different the "A" is in "Flame tank" and "Artillery". Look at how the "T"s are longer on the top left and shorter on the top right. Look at how different the top and bottom of the "B" in "Buggy" is (and notice "Sandbags" is correct).
fullbilinear.png is actually hermite scaling. I'll be honest, I have no clue what these words mean. It looks similar to bilinear though, and look, the artifacts in the nearest image are nearly gone here. Obviously, it's a more accurate depiction of the source image
doublebiliniear.png is a clean 2x resize followed by hermite scaling the rest of the way. Looks much sharper than the full bilinear that some scaling options gives you, but artifacts are still pretty hard to spot.
Of course GPU manufacturers go with doing bilinear scaling because it will always look accurate to the source image. Well Nvidia does that anyway. ATI doesn't seem to give a crap what the source image looks like because IIRC, they even do artificial sharpening in their scaler...