1. Backup any critical files and settings.
(mail and ISP passwords)
2. Verify that all hardware is on the W2K HCL.
(hardware compatibility list)
3. As OpatzG stated, download ALL drivers.
Save them to floppy, or on a CD.
4. See if you can boot from the W2K CD.
If not, you need to run the utility on the CD to create a boot floppy.
5. Boot from a W98 startup disk.
6. Run fdisk
delete at least the primary DOS partition.
7. Exit fdisk.
8. Shut down.
9. Boot from the W2K CD or startup floppy.
10. Run setup, and install W2K
11. Install the W2K drivers for your hardware.
12. Run Windows update
I would go beyond OpatzG's recommendation on RAM.
Install as much as the system will take / you can afford.
One side note:
If you use your PC for gaming, make sure the games you play run on W2K.
It is NOT very game friendly.
If you play games, you may be happier with XP Pro.
Chas