Need advice on multi-server setup

We have a small online classic card game realm (spades, hearts, gun, etc) that usually has a few hundred people online simultaneously. I am seeking advice on our current server setup and our plan to buy and integrate a new server.

Our current setup is like this:

Server 1
Database (sql 2000), cold fusion and web server run on a 4U dual xeon 3.0, 4gb ram, sbs 2003 premium, raid 5, 6-73gb 10k hs.

Servers 2 and 3
game servers that process the gaming software, 1u, xeon 3.0, 2gb ram, xp pro


We want to buy a new DB server and use it for the DB only and use the existing DB server as the web,cf and mail server.

Part of my question deals with my lack of knowledge on multi-core servers. Our existing DB server shows 4 cpu's in task manager and cpu 4 is always running high, while cpu 1 and 3 seem idle, cpu 2 always runs at about half of cpu 4. I am just wondering if we are using the full potential of its processing power. Why would a multi-core system not spread the workload evenly over all available cpu's? Should I be looking at Dual cores or quad cores for the new db server?

The game servers are connected to the DB server server through a cisco switch and a single network cable runs from switch to the db server.

I appreciate any advice anyone may have for me.

you say dual Xeon 3.0, i'm assuming you mean two Xeons, and it shows as 4 CPUs, and runs at 3Ghz, correct? that sounds like the hyperthreaded Xeon, in short, its not dual core, its single core. The OS should know this and should allocate stuff pretty much based on the real cores, so CPU1 and 2 should be treated as one, and CPU3 and 4 should be treated as one, on windows that may result with with 1 and 3 high, and 2 and 4 somewhat lower, depending on the system load

as for getting a bigger server, well first change your RAID level on the DB server, use RAID1 or RAID10, its much much faster, and thats very important for a database, and for the CPU get dual dual core (the new Xeons, maybe dual quad), that should be significantly faster then what you have