For these reasons, you will often have trouble installing CPAN modules

You're overstating the case. Granted, I'm a sample size of one, but, although my primary job description is "Perl programmer", I'm also the local devop[1], so I maintain several boxen running a mix of distros[2], some of which are rather ancient[3]. With the exception of Perl 5.8.x vs. 5.10, I have never encountered an issue with a CPAN module failing to install due to the system perl being too old. OP said he's currently on 5.10.1, so my experience suggests that this should not be an issue for him.

[1] ...and used to be a full-time sysadmin, once upon a time.

[2] The ones I install tend to run Debian and legacy systems are mostly Red Hat, but just about anything can pop up on occasion - SUSE, Mandriva, you name it.

[3] The current oldest is a Fedora Core 5 server, which we finally managed to start moving things off of just last week.