Security Update for Microsoft .NET Framework, Version 1.0 Service Pack 3 (KB930494) fails

I had a home visit from a Dell technician (my Dell Inspiron 6400 is still under guarantee) to fix memory card/motherboard problems which ended with him re-installing Windows XP Media Centre Version 2002 SP2. All seemed ok until after he left when I checked for updates and 88 were required - all failed to install. I checked the Microsoft forums and found advice to register the wups2.dll file (http://support.microsoft.com/kb/943144). This worked for 87 updates but the .Net Framework KB930494 update failed and continues to fail. I've tried the advice at http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?query=Security+Update+for+Microsoft+.NET+Framework%2C+Version+1.0+Service+Pack+3+%28KB930494%29&dg=&cat=en_US_d02fc761-3f6b-402c-82f6-ba1a8875c1a7&lang=en&cr=&pt=&catlist=&dglist=&ptlist=&exp=&sloc=en-us ie remove all trace of .NET Framework and reboot/reload but that didn't work either...I have no .NET Framework programs when I look at CONTROL PANEL/ADD OR REMOVE PROGRAMS and KB930494 still fails to load.  

Next I found advice (I can't remember where and can't find the link now) to download a cleanup program. I ran that but no difference - except that it made things worse. I still get the KB930494 failling to install, but when I started Adobe Reader, I got 'This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix this problem' It hasn't!

 This all stems from the memory card/motherboard failure and subsequent Windows XP reinstall carried out by Dell under guarantee. They don't want to help, saying that data is my responsibility. This is not data, it's the operating system!

There are dozens of posts  about this problem but none of them has fixed me up. Anyone got any new ideas?

Update: 2 hours later. Found Windows XP Service Pack 3 update was available so tried to install that, reckoning that it will all be fixed in the new SP and my problem will go away. After an hour's wait, the SP3 update failed. I'll work on that and hope this SP3 update fixes everything. I've found a link which reports updates to make before SP3 is installed - I'll read that tomorrow