Group policy - Win8 + IE10 and XP + IE8

a policy is set for Windows 8 and IE10 users

But sometimes, the Win8 users have to logon XP machines with IE8.

i find in Win8 group policy, the internet config can be set IE10 (1st) and IE8 (2nd) priority 

but it does not work when the users logon XP with IE8.

Thanks for your help