I've had great success with this:
#include <iostream>
#include <windows.h>
int main() {
ShellExecute(NULL, "open", "path\\to\\file.exe", NULL, NULL, SW_SHOWDEFAULT);
}
If you're interested, the full documentation is here:
http://msdn.microsoft.com/en-us/library/bb762153(VS.85).aspx.