To work on the cortex-m3 processors, you should meet the following requirements:
1. Software requirements: You should install an integrated Development Environment in your computer, such as Keil RealView MDK or IAR EWARM.
for Keil RealView MDK, you can download the evaluation edition or purchase the authorized edition from www.Keil.com
for IAR EWARM, please visit to www.iar.com
2. Hardware requirements: you should have one evaluation board which is based on ARM cortex-m3 processor, and one JTAG Debugger for cortex-m3, then you can download flash and debug your programs.
for evaluation board for cortex-m3, please visit http://www.embedinfo.com/en/list.asp?id=39
for JTAG Debugger, please visit http://www.embedinfo.com/en/list.asp?id=42.