I think that faust's underlying concept is that if you don't have physical security then you can be owned?

I can understand MS not shipping it with a password - as it would have to be the same default password on every installation, which is tantamount to not having a password in the first place.
That is very true, but I do agree that home editions should at least prompt for a password and let the user decide.

Agreed they should force a user to initially set a password in XP home (XP Pro does prompt for one) but residential users don't like being forced to do anything and MS is at the end of a day a business like any other and needs to keep their home user customer base happy.
Yes, the approach is consistent with earlier domestic versions of Windows, but domestic computers are now at much more of a risk than they were back then.