CMYK is a vector graphic format and RGB is a pixel based format. The two are completely different. Color Management is most used when out put to a Service Center and for the most part from what I have learned from them is that you really only need to use a default color profile for RGB when creating or viewing your work on the computer... when you take something to them or have them do the printing for them if needed "they" will apply a correct color profile for you. However there isn't anything wrong with applying one yourself but there are many for many reasons, If you have Adobe Illustrator version 7 on up and have all of the hard copy documentation that comes with the box it has an excellent small book on color management and the differences and uses of it. Adobe Photoshop abd Corel Suite also have extensive electronic and hard copy documentation of the subject but in my own opinion a common rgb profile applied to your artworks (sRGB IEC61966-2.1) and or an ICC Profile when exporting JPG's for the web allow others a generic profile that affords ready printable images from your desktop. When you get off into the CMYK world in that sense the same basic generic rules apply however depending upon what type of job you are sending to have printed or whatever machine it is being printed on will dictate the type of color mangement profile to embed into the work. When utilizing a software like say InDesign 2 or Quark you may well have mixes of both RGB and CMYK art throughout it (the publication that is...) and then you will need to read up more regarding "Bleed" and "Spot Colors" and when you do those attributes will explain in depth the reasons for color management and when it is best to utilize a particular profile or not at all. Your local Public Library and even better yet a local print shop will have all kinds of Art Print documentation the local print shop will "I am certain" be more than delighted to answer questions you might have regarding this topic and you should walk away totally enightened by the better understanding and knowledge you have attained as well as the smarts you exersized using the initiative to ask. :) I hope that, that at least helped to answer your question. That is a very good question and something that every artist should know about. Good luck!