Interfacing issue MicroSD

Hi guys, I need a few things cleared up, I've been building a robot(pretty complicated one at that) for the last 2 months.

I have figured out how to interface with the MicroSD and the Voicebox, both from sparkfun, separately. However, will using both of them at the same time cause problems? Also I am using several software serial connections to communicate to other Arduino Duemilanove, one to control Voice Commands and the other to control movement of the body.

This is the MicroSD shield I have sparkfun.com/commerce/product_info.php?products_id=9802

Along with this voice box, sparkfun.com/commerce/product_info.php?products_id=9799

If i need to clarify let me know, but any and all help is greatly appreciated.