i am about to set up my company and i was going to use fastservers to get my servers

i was going to get
Celeron 1.2Ghz
512MB of RAM
60GB IDE Drive
Red Hat Linux 7.3
1 Mb/sec Burstable Bandwidth or
300GB Actual
4 IP Addresses
24 Hour Active Port Monitoring

Personal System Administrator
Discounted CPANEL License
Live Bandwidth Reports
MAE-West Dual OC3 Connection
Free Off-Server Backup

how many customers whould you put on a sever this size also what would i also need to set this server up ready for customers