Lync 2010 - Upgrading to RTM and Web Components failing to install.

We accidentally waited too long to update our RC to RTM, and our Front End service was failing to start this morning.

Thankfully, I found this blog entry that Mike Stacy wrote on how to migrate fro m RC to RTM fairly painlessly.
http://mikestacy.typepad.com/mike-stacys-blog/2010/11/upgrading-from-the-release-candidate-of-lync-to-rtm-completely-unsupported.html

And everything worked as expected until I got the below error:
Error: Error returned while installing WebComponents.msi(Feature_WebComponents_CommonFiles,Feature_WebComponent_AddressBook,Feature_WebComponent_AuthFramework,Feature_WebComponent_AdminUI,Feature_WebComponent_CertProv,Feature_WebComponent_DataMCUWeb,Feature_WebComponent_DevUpdate,Feature_WebComponent_DialinPage,Feature_WebComponent_GroupExpansion,Feature_WebComponent_JoinLauncher,Feature_WebComponent_LocationInfo,Feature_WebComponent_MeetingMCUWeb,Feature_WebComponent_OcsPowershell,Feature_WebComponent_Rgs,Feature_WebComponent_ReachWeb,Feature_WebComponent_WebTicket), code 1603. Please consult log at C:\Users\clehradmin\AppData\Local\Temp\Add-WebComponents.msi-Feature_WebComponents_CommonFiles,Feature_WebComponent_Addres~-[2011_02_28][10_26_37].log

Checking in that Web Components log file, I found:
MSI (s) (4C!74) [10:32:06:364]: Product: Microsoft Lync Server 2010, Web Components Server -- Error 29024. Error 0x80004005 (Unspecified error) occurred while executing command 'C:\Windows\system32\inetsrv\appcmd.exe'. For more details, check log file 'C:\Users\CLEHRA~1\AppData\Local\Temp\LCSSetup_Commands.log'.

Checking the LCSSetup_Commands.log, I found this:
Filename: \\?\C:\Windows\system32\inetsrv\config\applicationHost.config
Line Number: 428
Description: Cannot add duplicate collection entry of type 'add' with unique key attribute 'name' set to 'OCSAuthHelperModule'

I edited the ApplicationHost.config, removing the below line for that Module, and was able to then reinstall!

This got me past that issue. Hope this helps someone else.