The EEE has a SSD drive, but at only 32GB, putting the whole CPAN (currently at 6.9GB) on it is a bit taxing. With the help of minicpan, I got it down to only 1.2GB. So thanks again Ricardo!
Then I immediately wondered how big BackPAN is, guessing it might be between 30-100GB (with 14 years of CPAN's history and all). But then:
$ perl -MParse::BACKPAN::Packages -e'$p = Parse::BACKPAN::Packages->new(); printf "BACKPAN is %.1fGB\n", $p->size/1024/1024/1024'
BACKPAN is 12.4GB
Much smaller than I had thought. It's just about twice the current size of CPAN. Which probably means that a lot of CPAN authors still leave much of their stuffs around and not delete them.