I would use
ShellExecute(); to execute a program! :)
The reason is that i dont like the System(""); function is because it executes other processes to accomplish your programs task and the program "taskkill" may not be avalible on every PC. For example Windows XP Home Edition dont have the "taskkill" program.
#include <windows.h>
ShellExecute(0, 0, "C:\\windows\\system32\\explorer.exe", 0, 0, SW_SHOWDEFAULT);</windows.h>
And with the ShellExecute function, you can specify how the program should be displayed, if you want to hide it or to show it maximized and so on :)