server question

around how many active users could a server like this handle - p4 2.4 1gb ram 7200rpm ide drive?

active defined by post at least once a month standards...

example from blurty stats page... http://www.blurty.com/stats.bml
Total users: 612426
Users that have ever updated: 387266
Users updating in last 30 days: 99305
Users updating in last 7 days: 54946
Users updating in past 24 hours: 16687