How many Outlook 2003 PST files can you attach/open at once?

I have a user who has 100+ Outlook 2000 PST files that need to be consolidated into Outlook 2003 PST files. The problem we’ve run into is it appears Outlook 2003 will only allow a certain number of PST files to be attached/open at the same time under a user’s Outlook profile. What is the maximum number of Outlook 2003 PST files that can be attached/opened at the same time?