Our SQL server is Large it is shared though with several apps that we run. 24 CPU 3GHz 192 GB RAM Windows 2008R2. We have 3 SQL instances one for our Alert processing (Netcool), one for SolarWinds, and another for ITM which will be retired soon because we replaced it with SolarWinds 
Our Pollers are spread across 2 DC with 1 poller in a DMZ layer in each DC and the 4 DC in the core network, our DCs are in Chicago and Columbus. I hope this helps