You're *probably* OK with the Deore BUT be sure: calculate it.
Everything you wanted to know about derailleur capacity:
http://sheldonbrown.com/gloss_ca-g.html#capacity
...and how to adjust one:
http://www.sheldonbrown.com/derailer-adjustment.html
Here's a page with a bunch:
http://www.travelbybike.com/bikepart...ail/shift.html
(I'm considering the "Shimano 201")