Dear Girtrude
Just to clarify your post re Stealth routers - I take that to mean that your router does not actively block ports but instead does not reply to uniniated incomming requests - If so I'm doing the same.
I think that the Mac community (and linux in time) will have to follow the same precautions that Windows users have done in the last 10 years or so.
To anyone reading this: there are sites that check the stealth status of your router (that's not the same as your computer by the way) - try putting "checking the stealth status of your home router" into any of your favorate search engines (without the quotes).
The resuls may require a bit of work to clarify but you will be a happy user in the long run.
I have learned the hard way.
CAT III