Just spending a few days of Christmas 'downtime' getting to know Ruby on Rails. Tried out InstantRails with no problems but decided that I'd like to use cygwin, partly so that I understand how the various bits of rails fit together without the InstantRails magic, and partly because the Unix like environment seems a bit more 'native' to Ruby on Rails.
Cue, loads of problems.......
1. need to ensure that gem is up to date - "gem update --system" seems to help here, but then you need to uninstall/install rails and rake.
2. problem with /dev/urandom can be at least bypassed by making self.supports_urandom? return false in secret_key_generator.rb.
3. Following Agile Development with Ruby on Rails, but using Rails 2.0.2 means that 'scaffolding' has been deprecated. This can be fixed with "ruby script/plugin install scaffolding"
After all that, decided to revert to Rails 1.2.6, as this should make following the book easier.