You need a new hard disk and some software to clone the current one. Clonezilla http://clonezilla.org/) is probably a good choice. With any luck you will be able to clone the old disk to the new one; if not you may have to reinstall Windows 2000 from scratch and see if you can access the old disk and copy what is readable to the new one.
You may want to find someone local who knows about these things, such as a mom and pop repair shop, to help you. It is very easy to lose all of your data, assuming it is still accessible, if you make a mistake.