|Depends on what you want. |
Just to use the drive as storage, you don't need any . Windows Vista ought to install it. Just plug it in and copy file to it.
If you mean some sort of backup or encryption that came with it when you bought it then go to the OEM web site. For example if it was a seagate then go to seagate's web page. Find your model and see if they have the software.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.