If you prefer pixely style you can use "windowed fullscreen" mode and choose a low resolution like 640x480 (or 854x480 for widescreen). You might also want to change the resolution filter to "point" to avoid blurring the stretched image. Note that while texture filters affect how images are resized, higher resolutions are not achived by just using some algorithm to resize stuff, there are actual high resolution textures and images being used since 1.7.