Digital BW, The Print

This may not sound like an intelligent question, but I am new to digital 
printing.

I use a brand new Epson R220, and am experimenting with printing using MIS 
UT-R2 inks on EEM paper.  I have read almost everything I can find about 
printing, etc. from this list, as well as a few web sites.

My question is, do I need to convert a file into black and white before I 
print it?  I have used Photoshop 7, done curves, converted and printed.  I 
also, just now, sent an image directly to the printer from Picasa II, with 
no intermediary processing.  Both prints are nearly identical.

I have done B&W darkroom processing for many years, so am more comfortable 
with that process.
Thanks for any help on this most likely simple question.

Frank Vincent