Need help replacing valve in shower

I am replacing a tub/shower and the faucets. I have a question on the valve though. The old valve is sweated in copper. The new valve is threaded. What is the best way to connect this valve? Should i just cut off the the old valve and insert compression nuts on all four connections? Or do i need to solder the connections? If so, what type of insert am i looking for to connect the valve to the pipe?