You CANNOT uninstall Windows 2000 Pro.
However, you can edit boot.ini to automatically boot to Windows XP Pro and delete Windows 2000 Server system files to save space.
1. Boot to Windows XP Pro.
2. Edit boot.ini by navigating to My Computer (right click) < Properties < Advanced < Startup and Recovery Settings and choose ?Microsoft Windows XP Professional? /fastdetect as Default operating system. And enter OK < OK.
3. Navigate to Startup and Recovery Settings as above and press Edit on ?To edit the startup options file manually, click Edit.?
4. The boot.ini Notepad opens. Delete the line that belongs to Windows 2000 Server under [operating systems]. The line should look like ?multi(0)disk(0)rdisk(0)partition(1)\Winnt=?Microsoft Windows 2000 Server? /fastdetect?. It is a good idea to write the line down on a piece of a paper because you are going to delete the system files (Winnt folder as above). Please make an adjustment accordingly if the Windows 2000 system folder is listed differently.
5. Save the boot.ini
6. Restart the computer. You will notice that the computer will boot to Windows XP Pro directly.
7. Open Windows Explore and delete Windows 2000 system files.
If you need more help, please add a comment.