I may be wrong, but I don't believe you can "upgrade" from win 98 to Win 2000. Win 2000 is evolved from Win NT.
You would need to do a fresh, complete install but before you do so make sure your computer meets Win 2K's requirements.
Computer/Processor 133 MHz or higher Pentium-compatible CPU.
Memory At least 64 megabytes (MB) of RAM; more memory generally improves responsiveness.
Hard Disk 2 GB with 650 MB free space.
CPU Support Windows 2000 Professional supports single and dual CPU systems.
Drive CD-ROM or DVD drive.
Display VGA or higher resolution monitor.http://www.microsoft.com/windows2000/profe...eqs/default.asp
Check hardware and software compatability:http://www.microsoft.com/windows2000/profe...pat/default.asp
Finding out if your BIOS (basic input/output system) is compatible with Windows® 2000:http://www.microsoft.com/windows2000/profe...t/biosissue.asp
To work properly with Windows 2000, your computer must have a compliant Advanced Configuration and Power Interface (ACPI) BIOS