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In addition to the couple of screw drivers for replacing the drive itself, you could get an external HDD enclosure for your old drive. You can plug into your USB and use the old drive to keep extra files, or better still to backup your system.

You will need en external enclosure anyway if you are going to clone your system to the SSD. I used this method when I replaced by HDD with a SSD and it was really easy. Simsaladimbamba's post above describes it well.
 
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