1) build a monstrosity- Quad CPU Motherboard loaded with Quad Core CPU's all @3.0+ Ghz with 128GB DDR3 - 1000mb uplink (MS SQL is > MySQL format Databases, for processing large number of users).
That should hold around 10,000+ players.
2) Build more servers off your current spec, wich is probly about 1 Quad CPU dedicated with 12GB of DDR2 ram wich will only hold about 2,500 players max. so if you want to follow this trend, you may want to open other servers, just add servers until it seems balanced.
You still have time to deside before the release date.