External Harddrive??

New to the forum! Well just got my first macbook a couple days ago, and love osx compared to windows which i've been used to for so many years. and i can say that my PC has been off for the past few days ha. Well i got the basic style with an 80 gig harddrive, didnt expect to do much. So i picked up a mini hard drive a western digi. 160 gig.

now my question is when i start to read up more on dual booting linux, will i be able to store it on my external usb harddrive? i do have plenty more questions but i know thats what the search is for ;-) thanks!