On the eve of the Rule 5 draft, Baseball America has posted a list of all Rule 5 eligible players(see link in Recent Articles section, please). They show 30 Farmstros as eligible. In my speculation and previous posting I came up with 30, but some of mine were based on guesses of signing dates. The eight I posted as possibly eligible who according to BA are not:
Castellano, LHP(VSL Astros)
Martinez, RHP(VSL Astros)
Espinal, RHP(DSL Astros)
Figueroa, IF(VSL Astros)
As you can see, these are all low-level guys.
One name BA doesn't list as eligible is Doug Arguello, LHP, who spent an impressive 2008 in Salem. He resigned with Astros a few weeks ago, and I think he is eligible, which would bring the Astros number to 31. If this is the case, they should be able to protect all players from the AAA and AA phases of the draft, once the major league phase concludes.