If you are are still running Debian 5 ‘Lenny’ and require access to the apt repository you may of noticed it no longer works. This is because Debian terminated support for this version of there operating system as you can see from the below new post in February. However you can still access the ‘lenny’ repository by changing the repository in sources.lst
Security Support for Debian 5.0 terminated
remove the old repository including security.debian.org and add
deb http://archive.debian.org/debian lenny main contrib non-free
you will now able able to get the final updates for lenny and install lenny packages.