Outlook 2000 slow on Windows XP Pro

I have a user experiencing slow issues when opening email in Outlook on a machine running Windows XP Pro with 1gb RAM.I re-installed Office and upgraded to the latest Office 2000 Service pack. I have removed her MS Outlook settings and re-created them and it got slower. I have performed a detect and repair but it did not help. She wants to revert to her old Windows 2000 machine but its already been stripped for parts. Any ideas on what is causing slow Outlook performance?