Okay lets see here... The proccessor is decent, you wont have any problem with it, however my concern lies in the ram.
If you are also gonna run a MYSQL server, an OS with GUI (unless you use bash ofcourse), and a webserver on that setup, i reccommend increasing the ram a bit.
With the current setup, taking into conideration MYSQL, Webserver and an OS with GUI, id say you will be able to take in around 50 players without lag, after that, its gonna start lagging a lil bit, and if you take on more than 100-150, its gonna start lagging badly.