Are my Hardware requirements enough to use OpenFire and issues on Embedded and external DB

Hi,

I’m planning to start an IM for iOS and Android. I’ve secured VPS from some host with a dual-core 2.4Ghz Processor, 4GB RAM, 80GB Storage and like 5TB of Bandwidth.

I want to know if this is sufficient to use OpenFire and also anticipate around 25,000 concurrent users in a short time from launch?

With the DB, the scenario is as follows:

I’m using a Linux OS on my VPS. OpenFire has it’s embedded database, which if I use, would slow down the performance (read this on many forums here ) I have cPanel on my VPS, which also has MySQL installed.

So if I use the cPanel MySQL as my DB choice, would this be an external db scene (considering that both the cpanel and OF are installed on the same OS)? Also, is this a good thing to do and if somebody has used this method, can you please throw some light on the pros and cons of this and the number of concurrent users you’ve achieved.