Similar problem here. I final decided to make the jump and upgrade from 10.4 to 12.4 and I get a load of errors when I use the update manager, ......

W:Failed to fetch http://ie.archive.ubuntu.com/ubuntu/...source/Sources 404 Not Found
, W:Failed to fetch http://ie.archive.ubuntu.com/ubuntu/...source/Sources 404 Not Found
, W:Failed to fetch http://ie.archive.ubuntu.com/ubuntu/...source/Sources 404 Not Found
, W:Failed to fetch http://ie.archive.ubuntu.com/ubuntu/...source/Sources 404 Not Found
, W:Failed to fetch http://ie.archive.ubuntu.com/ubuntu/...source/Sources 404 Not Found
, W:Failed to fetch http://ie.archive.ubuntu.com/ubuntu/...source/Sources 404 Not Found
, W:Failed to fetch http://ie.archive.ubuntu.com/ubuntu/...source/Sources 404 Not Found
, W:Failed to fetch http://ie.archive.ubuntu.com/ubuntu/...source/Sources 404 Not Found
, W:Failed to fetch http://security.ubuntu.com/ubuntu/di...source/Sources 404 Not Found [IP: 91.189.92.184 80]
, W:Failed to fetch http://security.ubuntu.com/ubuntu/di...source/Sources 404 Not Found [IP: 91.189.92.184 80]
, W:Failed to fetch http://security.ubuntu.com/ubuntu/di...source/Sources 404 Not Found [IP: 91.189.92.184 80]
, W:Failed to fetch http://security.ubuntu.com/ubuntu/di...source/Sources 404 Not Found [IP: 91.189.92.184 80]
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, W:Failed to fetch http://ftp.ticklers.org/archive.ubun...-i386/Packages 404 Not Found
, E:Some index files failed to download. They have been ignored, or old ones used instead.


Looks like a lot of fundamental packages are unavailable, can some one assist, I don't want to change my sources list without some concrete advice

Thanks in advance.