Apples update didn't work for me: Boot Camp: iMac displays a black screen during installation of Windows 7

Question

Boot Camp: iMac displays a black screen during installation of Windows 7 - Apple Support
I have followed each of the steps listed in the link above with no success.
Prior to adding the extra drivers I was able to start the Windows install process up to reformatting the "Windows" Bootcamp drive. After that the computer would go through some instal processes and eventually restart. After the restart the screen would go black. The black screen lead me to the  Apple Support link above dated March 5 2015. After going through steps listed in the link above, I get an error message stating that the D:\Sources\instal.win. file cannot be located. I am forced to restart the computer at that point and theWindows install process attempts to start again but always ends up at the same point.
Note: I am installing windows 7 Pro from a DVD. I scanned the AutoUnattend.xml file and noticed that it refers to "Windows 7 ULTIMATE" but not "Pro" or any others that I could see. (see below). Could that be part of the issue?
Any feedback would be greatly appreciated.
<cpi:offlineImage cpi:source="wim:d:/sources/install.wim#Windows 7 ULTIMATE" xmlns:cpi="urn:schemas-microsoft-com:cpi" />
</unattend>
iMac (27-inch, Late 2009)
2.66 GHz Intel Core i5
16 GB 1067 MHz DDR3
ATI Radeon HD 4850 512 MB

Answer 1

Here is an over-simplified explanation of WIM and CLG files. Assume your DVD Media contains
W7- Ultimate
W7- Professional
W7- Home Premium
W7- Home Basic
WIM Files
File1
y
y
y
y
File2
y
y
y
y
File3
y
File4
y
y
File4
y
y
y
The File .wim will contains a compressed image which contains File [1...5].
The W7-Ultimate .clg will have 5 entries, with all set to 'Y'.
The W7-Professional .clg will have 5 entries, with 'Y','Y','N','Y','Y'.
The W7-Home Premium  .clg will have 5 entries, with 'Y','Y','N','N','Y'.
The W7-Home Basic .clg file will have 5 entries, with 'Y','Y','N','N','N'.
This allows a single .wim Image file on the DVD media to be used to install any of the 5 flavors of Windows. When you enter your product key, the Installer knows what specific W7 variant you have the key for and will tell the WIM to extract the specific files the installer needs to be extracted.
The following line
<cpi:offlineImage cpi:source="wim:d:/sources/install.wim#Windows 7 ULTIMATE" xmlns:cpi="urn:schemas-microsoft-com:cpi" />
is telling that a retail product key will be entered, which should go look for this specific .clg file (from the five you already have on disk).  You can test if it will work for you by changing this line to the following
<cpi:offlineImage cpi:source="wim:d:/sources/install.wim#Windows 7 PROFESSIONAL" xmlns:cpi="urn:schemas-microsoft-com:cpi" />
If it does not work, the other issue can be related to device discovery. Typically A: and B: device names are reserved for Floppy Drives. C: is your internal HDD.
D: can either point to the Optical drive, or the USB. The normal convention is that the removable media is named from Z: backwards. Y: and Z: are usually used for Network drives, so X: should be your USB. First try with the change to "Professional". If it does not work,