Outlook History Disappears with Service Pack 2?

Yesterday I got brave and finally installed Service Pack 2 to my Windows XP
Prof. program. At the same time I updated my Office XP program. I was
probably a year behind in updating them.

When I opened my e-mail program (Outlook) everything was gone?? I only had a
few messages in my in-box from 2003. My contacts had disappeared as had all
my stored e-mails (in-box, Sent, Deleted, Special Folders, etc.)??

I used the system restore process to reset my computer to a time before the
installation of Service Pack 2. I should mention that I recently (within the
last 2 weeks) changed ISP providers from Roadrunner to SBC Yahoo. Most of my
stored e-mail information was from the Roadrunner ISP. But I didn't think
that should make a difference?

What did I do wrong and how can I install Service Pack 2 and keep my
original Outlook configuration with all it's stored messages, contacts,
folders, etc.?

Thanks, in advance, for any help you can provide me.
Ray19