dull jpeg colors from raw files

hey all. new to iphoto forum. any help would be appreciated.

when i bring in raw files to iphoto and save them as high quality jpeg there is a major difference in color quality between the jpeg and the original raw file. we've talked to a genius and still haven't been able to figure out this problem. the jpegs are dull, muted, and dark. they look exactly the same on a mac but when files are viewed on a pc or printed there is a major difference.

so the bottom line question is, what is the best workflow to take raw files and get high quality jpegs to be printed? and can i do it in iphoto or must i use aperture or photoshop?

thanks in advance!