One of the notes above reminded me - If you haven't calibrated your monitor and created/obtained custom .icc printer profiles, you may not get exactly what you expect.
It's not like your reds will turn out to be green, and it depends on your sensitivity/tolerance. But a 1-time investment is well worth it. You don't need to go crazy (unless you're a pro publishing in magazines) - my X-rite device/targets were <$300 are a great investment (they make everything else look right also).
I consider it one of my few essential accessories, along with the LensAlign setup.