Re: Why won't vista install detect my hard drive?
Heh. I was going to say to check to see that the hard drive is set to master/slave/whichever.
To set the jumper settings, there is usually a key on the drive itself. If not, you'll have to consult your documentation. They may even be abbreviated. The usual settings are Primary/Master, Slave, and Cable Select. It has been a while since I had to mess with Hard Drives, but I think it will register as a slave if you remove the jumper as well. The Hard Drive manufacturers all do it a little differently.
So, you boot drive (the one with the operating system) should be set to primary/master by setting the jumper switch according to the diagram. And the other one (I'm assuming you're just adding a second drive) should be set to slave.
If you get those set properly, make sure that the drive is coming up in the BIOS menu that you can get to when your computer is just starting up. You can see the full list in the boot menu. It usually has a few letters that correspond with the manufacturer, followed by numbers which generally tell how large the drive is.