Thank NaCl and 肝肠寸断散 for the help.
But I am still confused about the drives. If I plug each of them alone, the driver configuration could see them both. But if I plug them together as master and slave, only primary master shows up. And I ran the dell diagnostic, the old disk went through the disk test (it didn't go through the confidence test, but it didn't give any warning either, I guess the disk is old? It's a 4GB western digit..) And I am also curious is after I plug in just the old disk, the system could detect it. But when I put the window reinstall CD to try to install windows, why nothing happened?
Thanks for the help.