If you can download the whole file on the command line, then the Linux kernel and glibc support files bigger than 2 GB. The problem is that version of Perl probably wasn't compiled large file support. It won't support files larged than 2 GB. In the 'perl -V' output look for any mention of 'uselargefiles'.

I am guessing you are using RHEL 2.1. RHEL 3 has a Perl with USE_LARGE_FILES compiled in. You might consider upgrading the OS. The other option is rebuilding Perl with that flag turned on.