it is possible to have 98 and 2000 in the same partition

1. install 98
2. rename program files dir to something else - program98 or similar
3. reset computer - DO NOT SHUT DOWN NORMALLY
4. install 2000, it will recognise that 98 is there and ask if you want to upgrade, answer no and insall in new dir

when all is complete boot 98, it will complain that it cannot find certain files or files are the wrong version, this is because it is looking in 'program files' for 2000, simply point it at the renamed 98 program files

2000 should boot normally

tony