Changing Permalinks and Previous Posts

Hello,

The upgrade to wordpress 2.6 has messed up permalinks to our blog. I have noticed other users on this forum with similar problems.

My question is: We are now considering changing permalinks to a date/title format from the default /?p=### suffix.

Does anyone know if changing permalinks settings will alter all previous posts, or will it only affect future posts?

thanks for your help.