Accounts for Multiboot configuration

Hello,
on my PC I would like to have both Windows XP and Windows 7 installed.
Is there any possibility to share the accounts between these systems,
such that user A on XP is also recognized as the same user on Win7?
EasyTransfer transferred the settings of these users, but assigned
different user IDs, so that files and directories owned by user A on
WinXP belong to an numeric account on Win7.
How could one circumvent this problem, so that the users can use their
files properly for both systems?
Alois