In a color-managed work flow, you can use the precision of color profiles to soft-proof your document directly on the monitor. Soft-proofing lets you preview on-screen how your document's colors will look when reproduced on a particular output device.
The reliability of soft-proofing completely depends, however, on the quality of your monitor, your monitor profile, and the ambient lighting conditions of your workstation area. For information on creating a monitor profile, see "Creating an ICC monitor profile" in online Help or Chapter 7 in the Adobe Illustrator User Guide