Hard Drive not recognized

I just built a new computer and I wanted to get my stuff off of my old hard drive, but when I tried to boot up, the computer would stall at the initial screen (with options for bios and boot menu). When I try and go into the bios, it stalls trying to load the sata port for the old hd and does nothing when trying to go into the boot menu. Occasionally it would recognize the hd and when I try and boot off the old hd it would stall at various points in loading Windows. The old hd worked fine in my old computer. The old hd is a seagate 500gb, about 3 years old, not sure the model. Is there anything I can do to fix it or is it toast? Thanks.

Some system specs:
Mobo: Asus Sabertooth X58
CPU: i7-960

First of all, you must recognize that your new computer CANNOT boot from your old HDD! That old HDD has on it a version of Windows customized with all the device drivers needed for the computer it used to be in. It does NOT have the right device drivers for your new machine, so it cannot be used as the boot device.

Now, I assume you have a new HDD in the new machine with its own new version of Windows installed on it. Then the old HDD is just a second HDD unit in the new machine. In that case you should be able to boot properly from the NEW HDD. BUT to do this properly, you should make sure your BIOS has its Boot Priority Sequence set to boot from the new HDD and NOT even try to boot from the old one. Then comes the question: once you're running this way, does Windows see the old HDD in My Computer, with all its files, etc. Or, is there a problem accessing it? If there's a problem, the old HDD may be going or already gone.

On the other hand, if trying to boot from the NEW HDD with both installed has trouble with detecting the old HDD, then maybe that tells you it really is or has failed.

Well, I had been running my new computer off of my old hd for the past couple weeks because I was waiting on the new hd, and it worked fine until I tried to put the new hd in. Also, when I have the old hd plugged in, I cant even get to the bios or the boot menu to boot off the new hd.