Windows 2000 professional setup

Hello, Can someone help me???

I'm trying to set up. I enter my windows 2000 professional key and I get...

Setup has determined that your computer's startup hard disk is new or has been erased, or that your computer is running an operating system that is incompatible with Windows 2000.
If the hard disk is new or has been erased, or if you want to discard its current contents, you can choose to continue Setup.

If your computer is running an operation system that is incompatible with Windows 2000, continuing Setup may damage or destroy the existing operation system.

* To continue Setup, press C.
CAUTION: Any data currently on your computer's startup hard disk will be lost.

* To quit Setup, press F3.

Thanks...

Jeff