what exactly do you want to do with the arp packets? if you a looking to inject them in order go after wep you only need to cap one and play it back. it looks like you are capping arps so you can use them in a fragment -forge attack, once again you shouldn't need too many.
arp packets give you an idea of a networks layout and the basis for injection, but alone they really arent that important, what you want is authentication packets.



