You'd think this would be in an FAQ or something, but after a quick search, I didn't find the answer to this question...

Just got my 8700C, upgrading from a 7290 with Cingular (obviously...). The 8700 shipped with its own SIM card. Should I use the one that was sent with the device, or take the one from my 7290? And why would I use one versus the other?

Thanks!