Change Main Hard Drive

I just got a new 640GB My Passport Elite for my birthday. My computer is low on HD space. The hard drive is 74.5GB with about 3GB left. I formated the external to a NTFS. Once I backup all my files onto the Passport how do I get my computer to save files directly to that instead of my computer’s internal hard drive?

That’s a Windows question.  But you will have to direct all of your file saves to the external drive.  However, just as you need to keep backups for your data on your system drive, you will need to keep at least one backup of your external drive.