How to change sim card type?

At the moment, i have a contract with t-mobile, on a motorola motoluxe, I'm not really satisfied with the services it provides and would like to buy an iPhone 4 instead however the iPhone 4 requires a microSIM is there any way for me to perhaps exchance my sim for a microSIM and keep my contract?

Take it to dynamo the magician, I'm sure he will be able to do it for you

You can cut the SIM down with a razor blade if you are careful, or you can purchase a SIM cutter, or you can purchase a replacement SIM directly from your wireless company.