Printing digital photos professionally?

You are right, most labs require that your image be converted to RGB before they get it or your colors will be off. You monitor can be calibrated with Spyder but then before you send the image out convert it back to RGB. Now it might look funny but it will look correct to their monitors and printers. Also you might just want to call ahead to the lab that you are getting them printed at and ask them what format the want. That way it saves you time having to go back and send another one if the first one is wrong. Good Luck and as always happy shooting! :)