what's best way for playing with kernel configurations and source code

Hi everybody, How you can reconfigure and also modify your source code without affected your system? Please, if you want to suggest a virtual machine is the best option, then could you tell me why? Thanks in advance. -- Best Regards, Mohammad Alshamlan <http://www.linkedin.com/in/maalshamlan/> ARCS: Advanced Real-time and Computing Systems Lab<http://arcs-lab.eng.fiu.edu/> Department of Electrical and Computer Engineering FIU College of Engineering and Computing 10555 West Flagler St. EC 3900 Miami, FL 33174