Is color management necessary?

I am a casual photographer and like to have quality prints. I
normally get very good color from Ofoto. However, I did have the
experience of having a photo returned from Ofoto developing that
printed white snow on my monitor as purple on the print.

I mainly want to avoid these large errors in developing. Is color
management necessary for this? I have read:

Yes: http://www.drycreekphoto.com/Learn/m...alibration.htm
http://www.luminous-landscape.com/tu...proofing.shtml
http://www.luminous-landscape.com/tu...-profile.shtml

No: http://kenrockwell.com/tech/color-ma...-for-wimps.htm

I am uncertain about how profiling works in my setting. I have no
printer and want to use a profile for my monitor from a developing
company (calypso for example)? I think I need to download a profile
from Calypso into my computer for the type of monitor/type of
developing I want.

Is this the correct approach?
Is any of this necessary really?