Can't install latest Excel 2003 security update on Vista

I can't get the latest security update for Excel 2003 (KB923088) to install 
on Vista RC2. All the other patches that were just released for Office 2003 
install fine, but not this one. After it failed the first time I rebooted 
and tried again as the first action after logging in, but got the same 
error. An XP/Office2003 workstation getting its updates off the same WSUS 
server can install the same update without any problem.

WindowsUpdate.log shows the following:

2006-10-11 10:41:16:286 1032 cf4 Handler MSP download: file EXCEL.CAB 
already exists in sandbox directory 
(C:\Windows\SoftwareDistribution\Download\S-1-5-18\e24dcecf1c443ba6b9bb6e186530efa8)
2006-10-11 10:41:16:395 1032 cf4 DnldMgr ***********  DnldMgr: New download 
job [UpdateId = {012B6FF5-1DCE-4E1A-B5F2-1C2C2FF8314C}.100]  ***********
2006-10-11 10:41:16:395 1032 cf4 DnldMgr   * All files for update were 
already downloaded and are valid.
2006-10-11 10:41:16:458 1032 cf4 DtaStor Update service properties: service 
registered with AU is {9482F4B4-E343-43B6-B170-9A65BC822C77}
2006-10-11 10:41:16:458 1032 cf4 Agent *********
2006-10-11 10:41:16:458 1032 cf4 Agent **  END  **  Agent: Downloading 
updates [CallerId = AutomaticUpdates]
2006-10-11 10:41:16:458 1032 cf4 Agent *************
2006-10-11 10:41:16:458 1032 cf4 AU >>##  RESUMED  ## AU: Download update 
[UpdateId = {5DF4702D-6108-43B6-A738-3B6A0E9F2D70}, succeeded]
2006-10-11 10:41:16:458 1032 cf4 AU #########
2006-10-11 10:41:16:458 1032 cf4 AU ##  END  ##  AU: Download updates
2006-10-11 10:41:16:458 1032 cf4 AU #############
2006-10-11 10:41:16:458 1032 cf4 AU AU setting pending client directive to 
'Install Approval'
2006-10-11 10:41:21:471 1032 cf4 Report REPORT EVENT: 
{E1CFF21D-DC96-4BB9-B891-F5F4F701BB32} 2006-10-11 10:41:16:458+1000 1 189 
102 {00000000-0000-0000-0000-000000000000} 0 0 AutomaticUpdates Success 
Content Install Installation Ready: The following updates are downloaded and 
ready for installation. To install the updates, an administrator should log 
on to this computer and Windows will prompt with further instructions:  - 
Security Update for Excel 2003 (KB923088)
2006-10-11 10:41:29:591 1032 b74 AU Launched new AU client for directive 
'Install Approval', session id = 0x1
2006-10-11 10:41:44:698 1032 cac AU WARNING: Returning due to error from 
GetDownloadProgressUx, error = 0x8024000C
2006-10-11 10:41:44:698 1032 cac AU WARNING: GetInteractiveInstallProgress 
failed, error = 0x8024000C
2006-10-11 10:41:59:517 1032 cf4 Report Uploading 5 events using cached 
cookie, reporting URL = 
 http://www.**--****.com/ 
2006-10-11 10:41:59:548 1032 cf4 Report Reporter successfully uploaded 5 
events.

I'm having  a similar problem, but on XP.  It installed fine on a different 
XP Pro machine on my domain, but not on another.  Strange and arbitrary.  No 
matter how many times I try, it won't install.  Some weird MSI installer 
error.  From the App log, I get:

Product: Microsoft Office Professional Edition 2003 - Update 'Security 
Update for Excel 2003 (KB923088): EXCEL' could not be installed. Error code 
1603. 

So I am not alone out there...My error code is 779 - also using RC2
-- 
John

PC: (XPS Gen 1) laptop
Mem 1 gb
processor P4 3.4
Video ATI 9800 256 MB
Vista RC2 build 5744
Base score 4.3