Exchange 2013 install Errors

Hello,

I am trying to install Exchange 2013 into our current Exchange 2007 SP3 environment. I am getting the following errors when I run c:\Users\administrator.DC\Downloads\Exchange2013>setup.exe /PrepareSchema /IAcce
ptExchangeServerLicenseTerms

1)One or more servers in the existing organization are running Exchange 2000 or 2003
2)Cannot find the Recipient Update Service responsible for domain

Since I have been with our company, we have allows had 2007. I assume there was 2000 or 2003 before, but I cannot find it anywhere in AD or ADSIEDIT.

Can anyone help me track down this phantom Exchange installation?

Also, the other error about the Recipient Update Service, I have read I can ignore this error, Said correct?

Thanks!