Calibre won't install on stock lenny. The glibc libraries are too old. You need squeeze.
I made it work quite some time ago by creating a chroot'ed partition, installing sid (squeeze didn't yet exist) libraries into that partition, then installing calibre. This was a royal bother and in the end I gave it up, but if you want to go down that road, then see
https://www.mobileread.com/forums/sho...92#post1185292.
You could also go the backport route to get the newer glibc. The problem is that glibc is used by *everything*. I started down this route and came close to bricking my server, so I don't recommend it. Better would be to upgrade to squeeze.