transfer to new server

["NetWork 2020" <NetWork2020 HongKong com>]

Hi,

my old linux's harddisk has a lot of bad sector, so I buy a new one 
and install on other PC.

How can I transfer the user account (include password) , home 
directory and mail to new PC ?

there are around 150 user and I don't know the password, I think I 
creat the user account one again... :( 

any suggestion ? Thanks a lot !

Regards