dual boot win98/win2000

I would set up Win 98 first as normal , and then install Win 2000. It should detect that you have another OS and let you keep it, and add the option to the startup menu.
The only thing is that Whatever partition you have Win 98 will have to stay as a FAT partition and not converted to NTFS.

Reference the following sites for Dual boot guides
1)wwww.pcnineoneone.com/howto/dualboot1.html
2)www.guru3d.com/tech/dualboot
3)http://forum.arstechnica.com/forum/ubb/Forum5