Adobe CS5 uses Camera Raw, that might have a better RAW processing than ACDSee. What version of it are you using?
It's not abnormal to observe that. For example, Aperture 3 handles noise better than Aperture 2 did, all my high ISO shots with my old Nikon D50 just got better in 2010
"Those who cannot remember the past are condemned to repeat it."
Santayana, George. The Life of Reason, Reason in Common Sense
, Scribner's, 1905, page 284
Montreal Street Photography