You can clone the hard drive using tools like Partition Magic, or Ghost. On
THIS page you will find a link for downloading Hiren's Boot Disc v.7.0.3. Pick "Free" as the download type, then wait for the timer to count down. Once downloaded just extract the file, then burn the image to a CD.
Hookup the new drive, and boot your machine using that disc, and clone the drive using Ghost. After that it's just a matter switching the new drive over so it's your primary drive. Don't delete the contents, or format the old drive until your statisfied that the it was a good cloning (give it a day or so). Then you can do as you wish with the old drive.