Active Directory Setups

In an ideal setup, what does everyone use for # and size of partitions in AD?

Seperate or combined OS, AD DB and AD Log?

Let’s say a company of 300-400 users or quantify your own company size(s) in your answer(s).

I am wondering what theadvantage would be to seperate, as seen in the install instructions vs. one partition as per the MS website suggestions on this. It seems to me that at least 2 partitions would be good and possibly 3, but I was looking for help and input from the folks that have been running them day in and out for a while now. 🙂

~Thanks in advance from all of you’all!