Dear experts,
I have w2k on a pc, use ntfs and have a folder where only 1 user has access.
I recently added dual boot to this pc. The same user has an account in both
w2k and xp. This user needs access to the folder from w2k and xp depending
on what the pc is booted to.
How can I do that?

I actually solved the problem myself.
It was necessary in XPpro to turn off "simplified security". Then I could
get to the full security tab, see the w2k account sid, and add the account
from xp for full control. Now this user has full control from w2k and/or
xp.