Can anyone point to a specific product from a Linux service org
(RedHat, SuSE[Novell], Xandros) that is comparable to say Windows SBS?

How familiar are you with the item you responded with? (however you
may have come into contact with it)

If you were a contractor or consultant, would you recommend this
product over the MS equivalent bearing in mind that you may not always
be the person to control/deal with/consult on it?

Just to note, I am not taking into consideration the learning curve
required for the product, since Windows products have their own curve
too, just that their documentation is outstanding and tends to be more
comprehensive than Linux versions on the whole.