Vista SP1 x64 Exchange 2007 EMC Install Error: "Exchange Server setup encountered an error"

I have tried for months to get the Exchange 2007 SP1 x64 Exchange Management Console to install to my Vista SP1 x64 computer but without success. I am receiving an error seconds after seeing the "Microsoft Exchange Server 2007 Setup Initializing..." screen stating: "Exchange Server setup encountered an error". C:\ExchangeSetupLogs\ExchangeSetup.log contains this:

[10/21/2008 3:55:41 PM] [0] **********************************************
[10/21/2008 3:55:41 PM] [0] Starting Microsoft Exchange 2007 Setup
[10/21/2008 3:55:41 PM] [0] **********************************************
[10/21/2008 3:55:41 PM] [0] Operating System version: Microsoft Windows NT 6.0.6001 Service Pack 1.
[10/21/2008 3:55:41 PM] [0] Setup version: 8.1.240.6.
[10/21/2008 3:55:41 PM] [0] Logged on user: domain\username.
[10/21/2008 3:55:42 PM] [0] Command Line Parameter Name='mode', Value='Install'.
[10/21/2008 3:55:42 PM] [0] Command Line Parameter Name='sourcedir', Value='D:\Install\E2K7SP1EN64'.
[10/21/2008 3:55:42 PM] [0] Command Line Parameter Name='fromsetup', Value=''.
[10/21/2008 3:55:42 PM] [0] ExSetupUI was started with the following command: '-mode:install -sourcedir:D:\Install\E2K7SP1EN64 /FromSetup'.

The account I am installing from has administrator access. UAC is turned off, etc etc. I am running the x64 version of the Exchange 2007 SP1 installer, not the 32bit version. The Application Event Log has this error:

Log Name:      Application
Source:        MSExchange Common
Date:          10/21/2008 3:49:57 PM
Event ID:      4999
Task Category: (1)
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      computername.domain.local
Description:
The description for Event ID 4999 from source MSExchange Common cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event:

2652
E12
c-RTL-AMD64
08.01.0240.006
ExSetupUI
S.M.Automation
S.M.A.PSSnapInReader.ReadStringValue
S.M.Automation.PSArgumentException
6be5
06.00.6000.16386
False

the message resource is present but the message is not found in the string/message table

Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="MSExchange Common" />
    <EventID Qualifiers="16388">4999</EventID>
    <Level>2</Level>
    <Task>1</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2008-10-21T19:49:57.000Z" />
    <EventRecordID>22983</EventRecordID>
    <Channel>Application</Channel>
    <Computer>computername.domain.local</Computer>
    <Security />
  </System>
  <EventData>
    <Data>2652</Data>
    <Data>E12</Data>
    <Data>c-RTL-AMD64</Data>
    <Data>08.01.0240.006</Data>
    <Data>ExSetupUI</Data>
    <Data>S.M.Automation</Data>
    <Data>S.M.A.PSSnapInReader.ReadStringValue</Data>
    <Data>S.M.Automation.PSArgumentException</Data>
    <Data>6be5</Data>
    <Data>06.00.6000.16386</Data>
    <Data>False</Data>
  </EventData>
</Event>

Does anyone have any idea why I am unable to run the Exchange installer?