on a partially-but-not-totally related note, my stupid LG phone (I have Verizon) isn't Bluetooth capable and a real piece, so my friend suggested I try to find a phone on eBay. How did that work out for you, Marcus? Just serach and find?
and to relate to your original question - as mentioned, SIM cards are not phone-specific. I used ot have Cingular and I went form a Nokia to a Siemens phone, just swapping the SIM cards. You'll have to make sure your numbers are saved to the SIM card as opposed to the phone itself, otherwise you won't get those numbers not on the card. Some info might end up a little out of whack due to different layouts, but it should be ust fine overall. Well, in my experience