speed up outlook 2000 email delivery

I have recently upgraded a user to a new machine. All the software is identical to her previous stuff. She had a PIII-600 256 MB of RAM and bumped up to a dual PIII-800 512 MB of RAM. RUnning w2k/sp2 and office2k sr1/sp2. We run exchange 5.5 sp4and the settings are to corporate/workgroup. She has her email stored in a .pst file locally. Since the switch her email is not being updated real time. Eventually it will come in, but she can click on send/receive email at almost anytime and it will pick up messages that have been sitting on the server. Is there anyway to speed this process up? I thought that was automatic with her configuration. Thanks!