Photoshop does a better job in resizing compared to ACDSee.
For downsizing, Photoshop's bicubic or bilinear interpolation are both good. Bilinear creates a slightly sharper image when downsizing.
A bit irrelevant ~~ upsizing:
For upsizing, can try Photoshop bicubic interpolation with Stair Interpolation (SI). SI is simple, instead of upsizing an image directly to, e.g. 200%, you do it in 7 steps, with 110% in each step. Troublesome but the results are better.
Another good program is that mentioned by shas3n. It uses a very good interpolation engine for resizing.