Cannot find the 'third-party security" products that prevent installation

What is my next step? 

I have tried everything  to remove 'third-party security' products, but still get the message.  The log which was not in my windows folder, but my Doc & Settings folder was just three lines long and does not tell me what product is still on my computer. My IT people tell me to wipe my computer.  Is there a product that will name the item that is halting the install?  the computer is clean/never had a virus and works perfectly except for not being able to install Sophos and is a bit slow). 

I have run Belarc Advisor for a complete look at my computer and do not see something unusual, but there is more information than I can interpret. 

I have until March 31 to get Sophos loaded before our University drops the Mcafee 8.5 which is reinstalled for now.

system 

IBM Thinkpad  R51 (2004)

Windows XP SP3

I have in the past emptied the temp folders in Doc & Settings and in Windows.  Maybe I removed an important log.

I have manually and using the install program removed Mcafee enterprise 8.5i

I have searched the registry for anything called Mcafee, Network associates, virus, spyware

I have cleaned with GlaryUtility, Registry Mechanic

I have removed some of the the Thinkpad security stuff, but not all

Removed adaware, spybot.

I have spent about 40 hours removing programs, running Sophos installer, reinstalling McAfee and uninstalling and using their cleanup too.

The computer came with a lite version of Symantec which was removed when Mcafee enterprise 8 was installed.