I looked everywhere to find Exchange 2007 VHD default password but no luck. If you had downloaded Exchange 2007 with Windows 2003 and you are trying to login, you will get a screen with following inputs, fill out the way I have givenbelow:
Log on to: LITWAREINC
Package details for Exchange 2007 VHD:
Microsoft Exchange Server 2007 SP1 VHD
This download comes as a pre-configured VHD. It enables you evaluate Microsoft Exchange Server 2007 SP1.