Finally i get the Windows 7 installed on the Mac Mini.
Then i tried to do the same for the MacBook but i couldn’t find the usb drive on the boot menu. After asking Google, it is found that for those Mac machines which are equipped with the super drive (dvd drive), they cannot be booted by external devices. I try to install the rEFIt boot manager but it still doesn’t work.
Finally i have to use the Boot Camp to install the Windows 7, but i have to find a DVD Windows 7 installer. Anyway, the Boot Camp is really cool and all drivers are automatically installed.