Ok, so cracked it finally after trying out a lot of flags from the documentation. Hope it's helpful for anyone else struggling with it.
#include<Windows.h>
int main()
{
STARTUPINFO si = { sizeof(STARTUPINFO) };
si.cb = sizeof(si);
si.dwFlags = STARTF_USESHOWWINDOW;
si.wShowWindow = SW_HIDE;
PROCESS_INFORMATION pi;
CreateProcess("C:\\Program Files\\Nero\\Nero 7\\Core\\nero.exe", NULL , NULL, NULL, FALSE, CREATE_NO_WINDOW , NULL, NULL, &si, &pi);
}//main
Note that Nero's GUI will show up, but some other exe's which you may try will start, but the window won't be visible. You'll be able to see the application in TaskManager though.