I'd be inclined to use split. For example:

#!/usr/bin/perl -w
use strict;

while (<DATA>) {
    my ($major, $minor, $revision) = split /\./;
    print "Major:$major Minor:$minor Revision:$revision\n";
    # Do other processing here
}

__DATA__
10.00.359
10.01.1000
10.02.2000
[download]

You can then use $major in whatever comparisons you want, store it in a hash, or whatever.

Note that the period (.) must be escaped in the split match, otherwise it would be taken to mean "any character".

Hope this helps,
Darren :)