Your post implies that you are still on snow leopard so ILIFE 08 or 09?
You can use Preview to test if changing color sync profile will change how the picture appears. (view soft proof profile) (never knew you could do this until I your post problem)
Also - contact or go back to staples store to find out what level software is on the mac they tested the CD on including ILIFE(Iphoto) level.
IPHOTO 09 was not as compatible with photoshop as 08 as I had some black and white pictures loaded into 08 fine (monochrome profile) - when I loaded some into 09 they were weird and had to change them to RGB profile within photoshop before importing again.
I think later versions of IPHOTO are suppose to be more photoshop compatible - so those may be accepting the CYMK profile with no problem.
I use RGB in Photoshop - because you have more options adjusting color and it works.