I am using Vista and just installed Microsoft Office2007. Today I woke up and had 2,651 emails in my inbox. They were not new, but multiple repeats of emails in my inbox. This same thing happened about a week ago, but with only 1000+ emails,and I manually went in and deleted all the multiple emails and cleaned up my inbox, which I needed to do. I assumed this was a one time thing because of the new installation. I have obviously changed my mind. How can I fix this?

This is not related to Outlook 2007 itself, but more likley the server you are configured to download your mail from? What did you just install from? Were you using Windows Mail before this? Did it import the accounts? Outlook has no ability to generate mail by itself, they are coming from somewhere. You need to find where, and fix the problem there. This can happen if you use POP3 to download your mail. Your previous email client kept track of what messages it had downloaded and that record was not present in your new installation. If your previous email client was webmail or IMAP this would also make sense as there is no downloading with those protocols. This will stop once all mail is downloaded, but unless you have Exchange, you will not be able to put the messages back, which means you can't see old mail in webmail anymore.