Removing special characters using Ruby, but not spaces

Question

I was looking for awhile on here and didn't quite find what I needed. I am learning Ruby(1.9) and am trying to do something basic with a text file. I am trying to use RegEx's to remove non-letters, and white space that is ONLY at the beginning of the line, ignoring spaces between tokens(I am trying to count words in the file, hence when I want the spaces between words to remain).

Ex:

555 r6ub6y i7s e7a0sy... w1o2w4.

To change to:

ruby is easy... wow.

What I have so far using the command-line to test ruby rubyfile.rb < test.txt:

$stdin.each do |line|
    line.chomp!.downcase!
    line.gsub!(/[^a-zA-Z]/, "") #this takes away my spaces!
    puts line
end

Answer 1

[^a-zA-Z. ]

add a space as well.