Chances are, with just a little work, you can extend the life of your current hard drive for a while.
Most people have tons of clutter on their hard drive.
Cleaning it up is not that difficult if you know what to do. First, uninstall any programs you no longer use. A list of all the programs you have loaded on your system will be presented. Second, archive data you don't access anymore to some kind of removable media, like rewritable CD's, Zip disks, or Jaz disks. They'll still be available, but won't be taking up so much space on your system.