ISO uncomplicated alternative to PictureViewer


OK I am a diehard fan of the old PictureViewer for just looking at jpegs etc, I can use other things for editing. PictureViewer scaled up beautifully, the window was clean, going full screen was easy, the quality was great. But it's the only program I still use with Classic and I'd like to give up on Classic. GraphicConverter, ViewIt, etc are fine but when you increase size of a pic, the quality blurs. Is there something quick and simple to use that is comparable in quality to PictureViewer?