Exchange Server 2007 can be installed into an existing Exchange 2000/2003 (hereafter called Exchange 2003, except where there's something particular about Exchange 2000) organization as one step...
Updated Jul 01, 2019
Version 2.0
Blog Post
BTW: you don't have to do string parsing when calling cmdlets. As usual, there is always another way. Please check out the PowerShell SDK, which explains this in more detail:
http://windowssdk.msdn.microsoft.com/en-us/library/ms714469.aspx
http://windowssdk.msdn.microsoft.com/en-us/library/ms714469.aspx