You may be able to use the disk disk but you need to buy a new license key. An OEM one or the disk will not work with the key. The disk may not work anyway, depending on exactly what type of disk it is. Some setup disks only work with certain models of computers.
If it is a full restore disk you have, it won't work with the new computer because of the difference in drivers, it probably won't boot.
If you are building a new system, you should get Windows 7 for it.