Originally posted by Transit
need more featured resizer presumably
You probably want a rescaler using bicubic interpolation.
Paint Shop Pro has it (not sure if there is a free version).
Try
The GIMP. It offers bicubic interpolation and many more cool image manipulation possibilities.
Or
RawTherapee. This one doesn't have Photoshop/Gimp like image manipulation features (clone tool, etc.) but everything you need for adjusting an image as a whole (tone curves, sharpening, WB, etc.). It really is very, very useful and loads RAW + JPEG files. It features a rescaler with the options "Bi-Cubic" and "Bi-Cubic (extra sharp)".
In any event, if your current software supports sharpening, you could try to first reduce your image to 160x160, then (over-) sharpen, i.e,. it is OK if the image looks oversharpened at this stage, and then further reduce to 80x80. This strategy normally produces images that look really sharp at the desired output resolution.