[alphadeity]

From what you said in your post, you should be fine. If you could tell me more information I would be able to answer your question a little bit better.

Hardware is very important, yes. But software is just as important. Tweaking apache, sql, and php is important as well as kernel tweaks.

I have a client with 12000+ user forum with over a million posts and 200+ active users on a server with a duron processor (1.2GHz)! Granted it has 4GB memory, which is one of the most important, but the server runs with minimal problems.