Given the nature of Outlook (i.e., it can connect to the variety of services and directories), your Outlook problems may not actually be caused by Outlook. For example, Outlook may seem to have hung but it's just waiting for a mail server, for example, to respond.

How did the problems go away the first time? Can you describe your problems? (What you were doing at the time? Were you trying to check email, for instance?)

Yes, as others said, Outlook 2003 is better and faster and it's more user-friendly in that it tells you what it's doing more often than before. OTOH, it may not solve your problem if it isn't Outlook that's causing it.

Also, as others said, upgrading (as long as you won't uninstall the 'old' version first) will keep your data. Outlook 2003 will automatically pick them up. You can/should of course export (back up) your data first before starting your upgrade exercise.