Will mini USB work with portable notebook speakers?

Hi. I want to hook up some speakers in my backpack so i can listen to music off of my phone at lunch. Now, after digging up some computer speakers, i figured out after 3 seconds that they are A/C power, and in order to make them portable, like running them off of a battery, that’s all D/C and i don’t feel like lugging around a converter. So i have my sights set on these http://www.amazon.com/gp/product/B0009WKBGC/sr=1-2/qid=1265425965/ref=olp_product_details?ie=UTF8&me=&qid=1265425965&sr=1-2&seller= they are USB, and I’m worried about them working with a full size USB to mini USB cable, like the data cable that comes with the droid. Will that work? it’s just data right? Or does it have to be full-size USB to full-size USB for it to work? Any help would be appreciated. Thanks!