I don't believe there is any way to get around it (besides moving to Outlook 2003). The only thing I can suggest is to move some email messages out of the NSF file to a temporary nsf file and then do your export. There is no limit to the number of times you can export the same nsf file. You could then later copy back in the email messages to the nsf file, remove the ones already exported and export to a different Outlook PST file.
If you need any help doing this please let me know.
I hope this helps