Dedicated Connect Host System Dream Configuration?

A system with a firewire/IEEE 1394 connector makes interfacing with professional cameras easier and offers better quality video. Get Windows 7 so you can listen to your audio input. Be careful to get a system with separate mike and headset connectors (not the four pole, single connector types). If you can find a notebook that can handle line level audio inputs, it's a plus.

Knowing the history of Apple and Adobe, I would stick with a PC. Not just around the Flash issue (which I don't believe will be an issue), but more around the fact that Apple likes to make significant back end changes to their OS with new versions, and it tends to break the functionality of the Connect Add-In so you are left waiting for Adobe to make changes to the Add-In to accomodate Apple's changes.

I peronally use FireFox, but I have seen little differnece in functionality or issues with other browsers. Since the meeting room runs in the Flash Player, it is prety browser agnostic.

For processor speed and RAM, just go with the idea that more is better. The more you get now, the longer your system will be relevant to everyday computing, and that matters most.