How do i get data off a bad hard drive?

I have a dell laptop running vista home premium.
My hard drive crashed and i got it replaced, i was wondering how to get data off my old hard drive.
I have plugged the old hard drive into an external hard drive case and connected it to my computer via usb.
It appears in 'my computer' but when i click on it i can not open it and it sometimes freezes my laptop.
Is there and good hard drive recovery programs that are easy to use? or any other tips to help me?

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