"Server Brand, Family Model and Server OS (security has to be top notch no opensource please �?"
Why do you think many of the top tech companies in the world use Linux?
If you mean you're bringing this in house, you'd better have a world class security expert to monitor it. Security for a legal firm would be a nightmare and any breach could be catastrophic to your companies reputation.
I for one, wouldn't offer any guidance as it needs in depth analysis by an expert in your field.
With respect, the fact you're asking theses questions suggests you don't have that level of expertise.