I am not certain on this but as far as I know, OpenVPN is a single threaded application. So, if you have a quad core, or even a processor with 8 threads, OpenVPN will only use a single thread. I herd this is because of a kernel limitation, but again, I'm not sure how true it is. Maybe someone else can clarify. But if so, I would be more concerned with providing adequate processing power to 1000 users, might be best to break it off into several different edge points. As far as memory, I am not aware of any 64 bit version of endian yet, so pretty sure your capped at 4gb anyway, or 3020MB realistically. A good enterprise SSD with a decent swap partition should help, but I have yet to attempt a custom partition size on install so I'm not quite sure.
If it were my install I'd probably setup 4 independent firewalls and balance the load between the 4 accordingly. Also being that you are using a community version within seemingly a cooperate environment, it would probably be best to have several machines setup and running in a "just in case" clause, 1000 users offline can be a lot to deal with
Author