I dunno how serious you want to be with resizing, but the popular choice would probably be large programs like PS/Imageready/Paint Shop Pro, though that's probably too much if you only want to resize. If you wanna resize multiple images, there are batch resize programs like BatchImage, jpegSizer, and Qimage.
For single-image, there are plenty progs you can find that do as little distortion possible, even this old printkey program I still use on occasion.
And MS Photo Editor, that comes with Windows? Just go to Image-->Resize. The quality still remains intact as much as possible.
Remember though, you aren't able to keep original quality when down-sizing, because you're basically deleting pixels. While upsizing "guesses" to fill in the necessary pixels and smoothens it out... while some progs do it better than others, they all do the same thing.