My old Gateway Notebook running Windows XP died (the power supply went and the computer won't power up). I bought a new HP notebook running Windows Vista. I'd like to recover some of my data and files from my old computer (and possibly reformat the hard drive so that I can at least sell the computer for parts). I purchased a 2.5" external hard drive case with a USB cable. Although my new computer recognizes the device when I plug it in, the computer doesn't assign it a drive letter. How can I access the data and files on my old computer hard drive?

You may have to mount the drive first. Check the instructions that came with the enclosure.

It may be that Windows has not assigned the drive a letter.
Right click on "My Computer"
Left click on "Manage"
On the left hand side of the window is a list of options.
Click on "disk management"
In the Computer Management Window check to see if the drive is there AND
Has a letter assigned to it.
If there is no letter assignation, right click on the drive either on the list or on the graphic display at the bottom
Left click on "change drive letters and paths"
I believe the next step is to click on "add"
After assigning a letter, exit out and see if your USB drive is visible in "My Computer"
You may want to reboot if it is still not there.